Robin

I noticed those bands in the stretched result during processing... but
wasn't certain if they were real. I will check out Christians image later
on.

Would seem that the new grating is off to a good start!

Tom


> ----------
> From:  staranalyser[SMTP:robin@...]
> Reply To:  staranalyser@yahoogroups.com
> Sent:  11 July 2005 16:30
> To:  staranalyser@yahoogroups.com
> Subject:  [staranalyser] Re: First light
>
> --- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> >
> > By atmosphereic lines, are you refering to all those broad water
> lines up in
> > the far red/near ir??
> >
>
> If I stretch the spectrum image, I can see various lines apart from Ha
> from around 5870 to 8670. Mostly from O2 or H20 in the atmosphere I
> believe. Christian Buil has a nice comprehensive anotated Vega here
> http://www.astrosurf.org/buil/us/vatlas/vatlas.htm
> I fancy I can see signs of most of the broad features in your
> spectrum. Not bad considering yours is 1/20 of the resolution :-)
>
> Robin
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

--- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
>
> By atmosphereic lines, are you refering to all those broad water
lines up in
> the far red/near ir??
>

If I stretch the spectrum image, I can see various lines apart from Ha
from around 5870 to 8670. Mostly from O2 or H20 in the atmosphere I
believe. Christian Buil has a nice comprehensive anotated Vega here
http://www.astrosurf.org/buil/us/vatlas/vatlas.htm
I fancy I can see signs of most of the broad features in your
spectrum. Not bad considering yours is 1/20 of the resolution :-)

Robin

Thats exactly the same resolution i came up with! ;-)

I don't know which of the spacers pete was using, I was too busy fiddling
with my guidescope focus. I'll experiment with varying distance more
carefully next time.

By atmosphereic lines, are you refering to all those broad water lines up in
the far red/near ir??

> ----------
> From:  staranalyser[SMTP:robin@...]
> Reply To:  staranalyser@yahoogroups.com
> Sent:  11 July 2005 15:30
> To:  staranalyser@yahoogroups.com
> Subject:  [staranalyser] Re: First light
>
> Hi Tom,
>
> I gave your spectrum a quick run through Visual Spec. The atmospheric
> lines are showing up nicely too. I make the calibration 29.5A/pixel
> which makes the grating distance about 25mm which is a bit under the
> minimum recommended for best resolution with the SC3. What sort of
> couplings does Pete use? If it could be arranged, adding one of the
> spacers should give a bit more resolution.
>
> Robin
>
> --- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> > That was with Pete's black and white SC3.
> >
> > Its certainly nice to have everything back up and running again!
> >
> >
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Hi Tom,

I gave your spectrum a quick run through Visual Spec. The atmospheric
lines are showing up nicely too. I make the calibration 29.5A/pixel
which makes the grating distance about 25mm which is a bit under the
minimum recommended for best resolution with the SC3. What sort of
couplings does Pete use? If it could be arranged, adding one of the
spacers should give a bit more resolution.

Robin

--- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> That was with Pete's black and white SC3.
>
> Its certainly nice to have everything back up and running again!
>
>

That was with Pete's black and white SC3.

Its certainly nice to have everything back up and running again!


> ----------
> From:  staranalyser[SMTP:robin@...]
> Reply To:  staranalyser@yahoogroups.com
> Sent:  11 July 2005 12:19
> To:  staranalyser@yahoogroups.com
> Subject:  [staranalyser] Re: First light
>
> Nice first light Tom and Pete
>
> What camera were you using?
>
> Good to see on QCUIAG your Newtonian and newly cooled SC3 camera
> back in operation again BTW
>
> Robin
>
> --- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> > <http://astro.neutral.org/tmp/vega.tif>
> >
> > Managed to get the first spectrum out of the new grating. This was
> Pete
> > using it on his LX200 instead of me on my newtonian, so its
> impossible to
> > draw any comparisons with the old grating, but it does seem to be
> working
> > very well, with clear hydrogen lines.
> >
> > Tom
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Nice first light Tom and Pete

What camera were you using?

Good to see on QCUIAG your Newtonian and newly cooled SC3 camera
back in operation again BTW

Robin

--- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> <http://astro.neutral.org/tmp/vega.tif>
>
> Managed to get the first spectrum out of the new grating. This was
Pete
> using it on his LX200 instead of me on my newtonian, so its
impossible to
> draw any comparisons with the old grating, but it does seem to be
working
> very well, with clear hydrogen lines.
>
> Tom

<http://astro.neutral.org/tmp/vega.tif>

Managed to get the first spectrum out of the new grating. This was Pete
using it on his LX200 instead of me on my newtonian, so its impossible to
draw any comparisons with the old grating, but it does seem to be working
very well, with clear hydrogen lines.

Tom

Hi all,

I have made a few minor changes and one major correction to the user
manual. (The formula for the calculation of dispersion given
under "Wavelength Calibration" was incorrect)

The revised version v1.1 is in the files, replacing the old version

Robin

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the staranalyser
group.

   File        : /Star Analyser 100 Instructions v1.1(beta).pdf
   Uploaded by : staranalyser <robin@...>
   Description :

You can access this file at the URL:
http://groups.yahoo.com/group/staranalyser/files/Star%20Analyser%20100%20Instruc\
tions%20v1.1%28beta%29.pdf

To learn more about file sharing for your group, please visit:
http://help.yahoo.com/help/us/groups/files

Regards,

staranalyser <robin@...>

Hi all,

First a couple of famous bright stars P Cygni and Beta Lyrae. No need
for long exposure with the SC3 modified webcam with these :-) They
would probably show up fine even with an unmodded Toucam

http://mysite.wanadoo-members.co.uk/astro2/spectra_19.htm

And something fainter Nova V1663 Aql is still blazing away in H alpha
30 days after discovery (mag 12.50 but pretty easy because almost all
the light is concentrated in just the one line)

http://mysite.wanadoo-members.co.uk/astro2/spectra_18.htm


Robin

Hi Robin

Thanks, yes, I did get the manual and was thinking that it didn't mention focal
length etc as a factor in the size of the spectrum image - but as a factor for
affecting image quality.

I was thinking, if we had perfect optics, we would have a point size star image
irrespective of focal length and so, the spectrum would be the same size and
angular resolution. Since we don't, and the star image becomes distinctly non
point at high focal lengths, we would be better to operate at a lower focal
length....

I guess I'll have to read Christians site a bit to ghet my head around it.

I'll do a few tests - but I have both rear cell and screw in reducers so I can
have a play... and let you all know of course..

Cheers

Rob

Quoting staranalyser <robin@...>:

> Hi Rob,
>
> Did you get your instruction manual? If not you can download it from
> the files section. It has a bit about what limits the resolution in
> there. (FAQ 12 in particular)  Christian Buil also has an in depth
> analysis of the converging beam slitless setup that most people use
> with these types of transmission grating.
>
> http://www.astrosurf.org/buil/us/spe1/spectro1.htm
>
> Reducing the star image size by reducing the focal length is useful up
> to a point, but as the beam through the grating converges more, it
> produces more abberations which smear the spectrum. You could add
> collimating optics to make the beam parallel, but then everything
> starts to get a bit complicated. I am working on it though ;-)
>
> I have not done any systematic tests on the focsal length effect but I
> have tried with and without a focal reducer (f9 and f6) and get
> similar results with my setup, so my sweet spot may be in between the
> two. For the reasons you mentioned, I tend to work at f6 mostly. It
> will be interesting to see what other people find.
>
> (Of course if you use a nosepiece screw in type focal reducer, screw
> it on after the Star Analyser, otherwise you will reduce the spectrum
> too!)
>
> Blue skies here at the moment. let's hope it holds out and you get
> some too
> Robin
>
>
>
> --- In staranalyser@yahoogroups.com, "robbieince" <home@r...> wrote:
> > Hi everyone
> >
> > OK - just got my package through - seems very professional.
> >
> > Since its rainy ;o( I've been thinking about this a bit. I guess we
> > need point sources if we have no slit and so, - can people confirm
> > that the focal ratio or focal length of the scope has no effect on
> the
> > dispersion and the size of the spectrum? Ie all other things being
> > equal, its purely based on the distance of the grating from the
> > detector?
> >
> > Is there any point in using a focal reducer to get a brighter image,
> > better tracking, shorter exposure etc?
> >
> > Just wondering....
> >
> > Rob Ince
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Hi Rob,

Did you get your instruction manual? If not you can download it from
the files section. It has a bit about what limits the resolution in
there. (FAQ 12 in particular)  Christian Buil also has an in depth
analysis of the converging beam slitless setup that most people use
with these types of transmission grating.

http://www.astrosurf.org/buil/us/spe1/spectro1.htm

Reducing the star image size by reducing the focal length is useful up
to a point, but as the beam through the grating converges more, it
produces more abberations which smear the spectrum. You could add
collimating optics to make the beam parallel, but then everything
starts to get a bit complicated. I am working on it though ;-)

I have not done any systematic tests on the focsal length effect but I
have tried with and without a focal reducer (f9 and f6) and get
similar results with my setup, so my sweet spot may be in between the
two. For the reasons you mentioned, I tend to work at f6 mostly. It
will be interesting to see what other people find.

(Of course if you use a nosepiece screw in type focal reducer, screw
it on after the Star Analyser, otherwise you will reduce the spectrum
too!)

Blue skies here at the moment. let's hope it holds out and you get
some too
Robin



--- In staranalyser@yahoogroups.com, "robbieince" <home@r...> wrote:
> Hi everyone
>
> OK - just got my package through - seems very professional.
>
> Since its rainy ;o( I've been thinking about this a bit. I guess we
> need point sources if we have no slit and so, - can people confirm
> that the focal ratio or focal length of the scope has no effect on
the
> dispersion and the size of the spectrum? Ie all other things being
> equal, its purely based on the distance of the grating from the
> detector?
>
> Is there any point in using a focal reducer to get a brighter image,
> better tracking, shorter exposure etc?
>
> Just wondering....
>
> Rob Ince

Hi everyone

OK - just got my package through - seems very professional.

Since its rainy ;o( I've been thinking about this a bit. I guess we
need point sources if we have no slit and so, - can people confirm
that the focal ratio or focal length of the scope has no effect on the
dispersion and the size of the spectrum? Ie all other things being
equal, its purely based on the distance of the grating from the
detector?

Is there any point in using a focal reducer to get a brighter image,
better tracking, shorter exposure etc?

Just wondering....

Rob Ince

Supernova sn2005cs in M51 with the help of a slit aperture. In
twilight skies too!

http://mysite.wanadoo-members.co.uk/astro2/spectra_17.htm

Robin

Hi again Adrian,

The AR coating will stand wiping with a soft cloth - treat it as you
would a lens surface - with respect.

Regards

Bob Hawksley
PHEL







--- In staranalyser@yahoogroups.com, "Adrian Jones"
<universalconstant@h...> wrote:
> Hi Robin.  The grating and accessories look great!
> I just wanted to ask you (or PH) about the recommended method for
> cleaning the grating; mine has some specks that won't blow off and
a
> couple of small smears.
>
> Is it safe to swab the exposed surfaces with my normal IPA +
distilled
> water cleaning mix?  Is the grating surface exposed or sandwiched
> behind glass ... any risk of liquid ingress at the edges, if a
sandwich
> construction? Etc.
>
> Thanks
> Adrian.

If anyone is interested in knowing the diameter of the grating
actually used in their particular setup, you can calculate it as
follows:

Diameter = sensor chip diagonal dimension + (grating to sensor
distance/scope focal ratio)

eg 12.5mm for a Toucam 40mm from the grating at f5


Robin



--- In staranalyser@yahoogroups.com, "patonhawksley"
<patonhawksley@y...> wrote:


> one or two small spots at the edge. This should not effect the
> working of the filter as the optical path would normally be
through
> the centre portion.

Hi Robin.  Thanks.  No, I didn't get a copy of the manual but have
just been browsing the online version.  looks very good and answers
my question about cleaning too.
I'll give you some proper feedback when I've gone through it more
carefully and had a go in practice ..... if the rain ever stops!

Adrian


--- In staranalyser@yahoogroups.com, "staranalyser" <robin@l...>
wrote:
> Hi Adrian,
>
> The manual should give some idea of what to go for first. As
someone
> new to spectroscopy I would be interested in your feedback on the
> user manual. It tends to be a bit difficult pitching these at the
> right level when one is familiar with the subject.
>
> As for targets, to start with I would suggest a bright A type star
> (Vega is an obvious one at the this time of year) These show sharp
H
> Balmer absorption lines which you can practice your focussing
> technique. Even easier are M type stars which show nice broad
> molecular bands which show up even without precise focussing.
> Betelgeuse is the best candidate but not at this time of year of
> course. How about Mirach (Beta Andromeda) or Scheat (Beta Pegasus)?
> though you might have to stay up a bit late for them to rise to a
> decent altitude.
>
> Robin
>
>
> --- In staranalyser@yahoogroups.com, "Adrian Jones"
> <universalconstant@h...> wrote:
> > Hi Robin, Tom and other 'staranalysers'.  Well, my grating and
> spare
> > bits arrived safely this morning, so here's hoping the weather
> will
> > cooperate soon.
> > I'll be starting from scratch, so any start-up advice from you
> more
> > experienced colour-splitters would be welcome.
> >
> > On the subject of testing and feeding back, Robin, have you got a
> > particular testing programme or sequence in mind, or is the idea
> just
> > to do our own thing and post results on a variety of subjects?
> >
> > I'd like to maybe work through a sequence of (increasingly
> > challenging?) subjects in order to build up my experience and to
> give
> > the grating a good test.  Just a suggestion: would there be some
> > mileage in defining such a hit-list - some objects we could all
> have a
> > go at as part of our testing and feedback?
> >
> > Adrian

Hi Adrian,

The manual should give some idea of what to go for first. As someone
new to spectroscopy I would be interested in your feedback on the
user manual. It tends to be a bit difficult pitching these at the
right level when one is familiar with the subject.

As for targets, to start with I would suggest a bright A type star
(Vega is an obvious one at the this time of year) These show sharp H
Balmer absorption lines which you can practice your focussing
technique. Even easier are M type stars which show nice broad
molecular bands which show up even without precise focussing.
Betelgeuse is the best candidate but not at this time of year of
course. How about Mirach (Beta Andromeda) or Scheat (Beta Pegasus)?
though you might have to stay up a bit late for them to rise to a
decent altitude.

Robin


--- In staranalyser@yahoogroups.com, "Adrian Jones"
<universalconstant@h...> wrote:
> Hi Robin, Tom and other 'staranalysers'.  Well, my grating and
spare
> bits arrived safely this morning, so here's hoping the weather
will
> cooperate soon.
> I'll be starting from scratch, so any start-up advice from you
more
> experienced colour-splitters would be welcome.
>
> On the subject of testing and feeding back, Robin, have you got a
> particular testing programme or sequence in mind, or is the idea
just
> to do our own thing and post results on a variety of subjects?
>
> I'd like to maybe work through a sequence of (increasingly
> challenging?) subjects in order to build up my experience and to
give
> the grating a good test.  Just a suggestion: would there be some
> mileage in defining such a hit-list - some objects we could all
have a
> go at as part of our testing and feedback?
>
> Adrian

Hello Adrian,

Glad you got your SA overnight. 4 went out yesterday and 2 more
today.

We had a few problems with our pre-production units (which I won't
bore you all with). We had to compromise on a couple and let them go
with one or two small spots at the edge. This should not effect the
working of the filter as the optical path would normally be through
the centre portion. However to the discerning eye it might look as
if it needs a clean.

The grating is sandwiched between 2 pieces of glass. I would not
recommend swabbing with your favourite solution as I cannot
guarantee you will not get an ingress of liquid. Bear in mind this
filter does not come to bits like some do. Surface smears on either
side can be cleaned by lightly wiping with a fine cloth.

Hope this helps.

Bob Hawksley
PHEL


--- In staranalyser@yahoogroups.com, "Adrian Jones"
<universalconstant@h...> wrote:
> Hi Robin.  The grating and accessories look great!
> I just wanted to ask you (or PH) about the recommended method for
> cleaning the grating; mine has some specks that won't blow off and
a
> couple of small smears.
>
> Is it safe to swab the exposed surfaces with my normal IPA +
distilled
> water cleaning mix?  Is the grating surface exposed or sandwiched
> behind glass ... any risk of liquid ingress at the edges, if a
sandwich
> construction? Etc.
>
> Thanks
> Adrian.

Hi all,

Great to here the first batch of Star Analysers are out :-)  Did they
come with an instruction manual? I was a bit late producing it so in
case you don't have one, I have put a pdf version in the files
section. I would be interested in your comments on this too.

Robin

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the staranalyser
group.

   File        : /Star Analyser 100 Instructions v1.0 (beta).pdf
   Uploaded by : staranalyser <robin@...>
   Description : Instruction manual v1.0 for beta testers

You can access this file at the URL:
http://groups.yahoo.com/group/staranalyser/files/Star%20Analyser%20100%20Instruc\
tions%20v1.0%20%28beta%29.pdf

To learn more about file sharing for your group, please visit:
http://help.yahoo.com/help/us/groups/files

Regards,

staranalyser <robin@...>

Hi Robin.  The grating and accessories look great!
I just wanted to ask you (or PH) about the recommended method for
cleaning the grating; mine has some specks that won't blow off and a
couple of small smears.

Is it safe to swab the exposed surfaces with my normal IPA + distilled
water cleaning mix?  Is the grating surface exposed or sandwiched
behind glass ... any risk of liquid ingress at the edges, if a sandwich
construction? Etc.

Thanks
Adrian.

Thanks, Tom.  I should have looked at your website first.  That's a
very useful tutorial you've produced .... everything I need to get
started!

My initial impression of the pack I received today is very good.  The
grating is in a nicely finished 'filter' cell and comes with two
empty filter cell spacers and a spare locking ring, all packed in
separate foam-lined filter boxes.

I'm posting a separate question to Robin to ask about cleaning the
grating (just a few specks and smears).

Adrian

--- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> Morning Adrian.
>
> Have haven't been home to check my post yet - what are you initial
> impression of all the bits?
>
> I'd suggest you kick off with a range of bright stars as I did here
> <http://astro.neutral.org/imagehtml/stars1/20041126_stars.html>
>
> and see the differing spectra of different types of star.
>
> Tom
>
>
> > ----------
> > From:  Adrian Jones[SMTP:universalconstant@h...]
> > Reply To:  staranalyser@yahoogroups.com
> > Sent:  05 July 2005 11:25
> > To:  staranalyser@yahoogroups.com
> > Subject:  [staranalyser] Hello
> >
> > Hi Robin, Tom and other 'staranalysers'.  Well, my grating and
spare
> > bits arrived safely this morning, so here's hoping the weather
will
> > cooperate soon.
> > I'll be starting from scratch, so any start-up advice from you
more
> > experienced colour-splitters would be welcome.
> >
> > On the subject of testing and feeding back, Robin, have you got a
> > particular testing programme or sequence in mind, or is the idea
just
> > to do our own thing and post results on a variety of subjects?
> >
> > I'd like to maybe work through a sequence of (increasingly
> > challenging?) subjects in order to build up my experience and to
give
> > the grating a good test.  Just a suggestion: would there be some
> > mileage in defining such a hit-list - some objects we could all
have a
> > go at as part of our testing and feedback?
> >
> > Adrian
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >

Morning Adrian.

Have haven't been home to check my post yet - what are you initial
impression of all the bits?

I'd suggest you kick off with a range of bright stars as I did here
<http://astro.neutral.org/imagehtml/stars1/20041126_stars.html>

and see the differing spectra of different types of star.

Tom


> ----------
> From:  Adrian Jones[SMTP:universalconstant@...]
> Reply To:  staranalyser@yahoogroups.com
> Sent:  05 July 2005 11:25
> To:  staranalyser@yahoogroups.com
> Subject:  [staranalyser] Hello
>
> Hi Robin, Tom and other 'staranalysers'.  Well, my grating and spare
> bits arrived safely this morning, so here's hoping the weather will
> cooperate soon.
> I'll be starting from scratch, so any start-up advice from you more
> experienced colour-splitters would be welcome.
>
> On the subject of testing and feeding back, Robin, have you got a
> particular testing programme or sequence in mind, or is the idea just
> to do our own thing and post results on a variety of subjects?
>
> I'd like to maybe work through a sequence of (increasingly
> challenging?) subjects in order to build up my experience and to give
> the grating a good test.  Just a suggestion: would there be some
> mileage in defining such a hit-list - some objects we could all have a
> go at as part of our testing and feedback?
>
> Adrian
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Hi Robin, Tom and other 'staranalysers'.  Well, my grating and spare
bits arrived safely this morning, so here's hoping the weather will
cooperate soon.
I'll be starting from scratch, so any start-up advice from you more
experienced colour-splitters would be welcome.

On the subject of testing and feeding back, Robin, have you got a
particular testing programme or sequence in mind, or is the idea just
to do our own thing and post results on a variety of subjects?

I'd like to maybe work through a sequence of (increasingly
challenging?) subjects in order to build up my experience and to give
the grating a good test.  Just a suggestion: would there be some
mileage in defining such a hit-list - some objects we could all have a
go at as part of our testing and feedback?

Adrian

Hi Tom,

There could be something in this. I was looking up about vignetting
the other day for another reason (I am starting to see vignetting
with my camera at the high focal reductions I can get with an ATIK
FR I bought recently.)

It is relatively easy to work out the aperture. To get all the light
available in the centre of the field, the stop has to be at least
the same focal ratio as the telescope. eg for f5, a stop at say
100mm would be 20mm diameter. This would then progressively vignette
(sp?) the field as you move away from the centre. (To get a
completely unvignetted field, the stop diameter needs to be
increased by the diagonal dimension of the CCD)

In the case you suggest, you could offset aperture by a few mm to
place the centre at the edge of the field and place the star there.
Of course the vignette will be dispersed through the grating as
well, so I am not sure if there will be a big (or any) advantage at
the end of the day. Worth a try though!

I fact, thinking about it, It should be possible to just mask the
diffraction grating itself to get the effect.

A focussed slit/aperture, even one kept wide to help tracking,
should give a big improvement and eliminate the need to miss the
other stars, but for that you need to add a couple of extra lenses.

Robin

  --- In staranalyser@yahoogroups.com, Tom How <tomh@t...> wrote:
> Hrm... guess I'd better put my telescope back together then - its
currently
> in bits all over the house getting its summer servicing and a few,
urm,
> modifications. ;-)
>
> Whilst we are waiting.. here is an idea I've been pondering for a
while....
>
> When imaging a spectrum of dim object (such as our old friend 3c
273
> <http://astro.neutral.org/imagehtml/20050408_3c273.html>) I have
the grating
> fairly close to the ccd to produce a short spectrum, about 25
Å/pixel.
> Usually the target object is close to the centre. See link.
>
> The spectrum is, of course, very dim, and the skyglow behind
it "ruins" the
> image of the spectrum to a certain extend... its pretty much our
limiting
> factor.
>
> In an ideal world, we'd have a slit at the focus of the telescope
just
> letting the light of our target through, and this light would then
be
> refocused onto a CCD - however, this sounds nightmereishly
difficult -
> aiming, tracking etc etc.
>
> I am wondering if there is some kind of halfway house..... I was
wondering
> what would happen if we put an aperture iris (eg pinched from an
SLR lens) a
> short distance in front of the grating. (ie telescope side, not
camera side)
> Setup the exposure normally with the iris open (ie no effect).
Once the dim
> target is centred on the ccd chip with its attendant spectrum
running off
> towards one corner, partially close the iris.
>
> With a bit of rough maths, based on the focal length/aperture of
ones scope,
> it should be possible to work out roughly how much to close the
iris so that
> it does NOT interfere with the light from the star, but reduces
the light
> from all other sources.
>
> Obviously it won't reduce the the background completely, but it
might reduce
> it a bit, especially up near the Ha (ie a long way from the
target). Even a
> slight attenuation of the background will help with signal to
noise ratio on
> the dimmer spectrum.
>
> All this assumes the target is pretty much centred and the
spectrum is short
> enough to fit on the ccd. IT only applies to those dimmer objects
where you
> are using a low resolution spectrum
>
> I've not tried this myself as I've not figured out a way to mount
everything
> - although this new grating will help with that problem. I've also
simply
> not had the time. (that curse of the dedicated QCUIAGer - too many
projects.
> I blame Arthur and Steve!)
>
> Thoughts?

Hrm... guess I'd better put my telescope back together then - its currently
in bits all over the house getting its summer servicing and a few, urm,
modifications. ;-)

Whilst we are waiting.. here is an idea I've been pondering for a while....

When imaging a spectrum of dim object (such as our old friend 3c 273
<http://astro.neutral.org/imagehtml/20050408_3c273.html>) I have the grating
fairly close to the ccd to produce a short spectrum, about 25 Å/pixel.
Usually the target object is close to the centre. See link.

The spectrum is, of course, very dim, and the skyglow behind it "ruins" the
image of the spectrum to a certain extend... its pretty much our limiting
factor.

In an ideal world, we'd have a slit at the focus of the telescope just
letting the light of our target through, and this light would then be
refocused onto a CCD - however, this sounds nightmereishly difficult -
aiming, tracking etc etc.

I am wondering if there is some kind of halfway house..... I was wondering
what would happen if we put an aperture iris (eg pinched from an SLR lens) a
short distance in front of the grating. (ie telescope side, not camera side)
Setup the exposure normally with the iris open (ie no effect). Once the dim
target is centred on the ccd chip with its attendant spectrum running off
towards one corner, partially close the iris.

With a bit of rough maths, based on the focal length/aperture of ones scope,
it should be possible to work out roughly how much to close the iris so that
it does NOT interfere with the light from the star, but reduces the light
from all other sources.

Obviously it won't reduce the the background completely, but it might reduce
it a bit, especially up near the Ha (ie a long way from the target). Even a
slight attenuation of the background will help with signal to noise ratio on
the dimmer spectrum.

All this assumes the target is pretty much centred and the spectrum is short
enough to fit on the ccd. IT only applies to those dimmer objects where you
are using a low resolution spectrum

I've not tried this myself as I've not figured out a way to mount everything
- although this new grating will help with that problem. I've also simply
not had the time. (that curse of the dedicated QCUIAGer - too many projects.
I blame Arthur and Steve!)

Thoughts?

Tom
> ----------
> From:  staranalyser[SMTP:robin@...]
> Reply To:  staranalyser@yahoogroups.com
> Sent:  20 June 2005 23:46
> To:  staranalyser@yahoogroups.com
> Subject:  [staranalyser] Re: Hello
>
> Hi Tom,
>
> Only me and thee in here at the moment :-( I will remind the others
> when the first batch is sent out. We have six Beta testers confirmed
> and one outstanding. Paton Hawksley should be starting manufacture
> later this week - Just awaiting delivery of a component.
>
> Robin
>
> --- In staranalyser@yahoogroups.com, "tomhow_uk" <tomh@t...> wrote:
> > Gosh its quiet in here.
> >
> > Whats the expected timetable on the gratings Robin?
> >
> > Tom
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Hi Tom,

Only me and thee in here at the moment :-( I will remind the others
when the first batch is sent out. We have six Beta testers confirmed
and one outstanding. Paton Hawksley should be starting manufacture
later this week - Just awaiting delivery of a component.

Robin

--- In staranalyser@yahoogroups.com, "tomhow_uk" <tomh@t...> wrote:
> Gosh its quiet in here.
>
> Whats the expected timetable on the gratings Robin?
>
> Tom

Gosh its quiet in here.

Whats the expected timetable on the gratings Robin?

Tom

Welcome to the staranalyser beta testing group

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