Thanks Curtis! From: CurtisC <calypte@...> To: ccd-newastro@yahoogroups.com Sent: Sunday, December 4, 2011 2:23 PM Subject: [ccd-newastro] Re: New...
70266
JoeMize
sfojmize
Dec 5, 2011 3:27 pm
Kerry, I'm sorry I saw no mention of CFW-8 in your initial post. Plz disregard my posts about the STL11K...joe :) "May You Go Among The Imperishable Stars" ...
70267
Erwin Kats
erwin_kats
Dec 5, 2011 3:39 pm
Hello, I recently joined this group to learn, but maybe also share experiences. I am 23 year old, living in Holland. On the age of 11 I started to get...
70268
Ken
ken4optics
Dec 5, 2011 4:17 pm
When you use, say a 250mm f10 SCT and the average seeing conditions are 3 arc second, the FWHM size of the star image will be 36 micron. If this is then imaged...
70269
Ron Wodaski
rwodaski
Dec 5, 2011 4:24 pm
There are two reasons why a star's image might get larger: * Movement of charge from pixels with a lot of electrons to pixels with fewer electrons (e.g., an...
70270
Stan
stan_ccd
Dec 5, 2011 4:57 pm
Apparent star "size" is a function of PSF (FWHM), S/N, and scaling. Visualize the cross-section of a star – it is essentially a Gaussian "bell curve"....
70271
Ken Harrison
ken4optics
Dec 5, 2011 5:03 pm
Ron, Thanks for that. We're not seeing the actual Airy Disk associated with the optimum resolution of the scope, but a Point Spread Function of an image. The...
70272
Ron Wodaski
rwodaski
Dec 5, 2011 5:08 pm
That would be true if the shape of the star profile were triangular, but as Stan pointed out, a Gaussian curve is a close approximation to the actual star...
70273
Bernard Miller
bgmiller_01
Dec 6, 2011 3:06 am
Hi, I captured this data last month and finally got around to processing it. This is a cropped version of NGC 891. You can just make out the dusty filaments in...
70274
Ron Brant
astroron2001
Dec 6, 2011 3:56 am
Nice image Bernard! Good work. Ron ... From: Bernard Miller To: ccd-newastro@yahoogroups.com Sent: Monday, December 05, 2011 6:48 PM Subject: [ccd-newastro]...
70275
Neil Fleming
neilfleming
Dec 6, 2011 11:34 pm
Welcome aboard. Nice Crescent shot. Cheers...Neil www.flemingastrophotography.com Direct from Boston - brilliant diamonds in pea soup Also check...
70276
Robert
rjhertel2001
Dec 7, 2011 11:24 pm
Could someone kindly explain why if my Starshoot Autoguider is an 8 bit camera, the ADU counts of a light frame as shown by cursor movement over stars via...
70277
Stan
stan_ccd
Dec 8, 2011 5:32 pm
... Was the frame aquired via MaxIm(?), in which case it might rescale 8 bits into 16 bits via multiplication. Or maybe the camera firmware rescales the...
70278
Douglas B. George
maximccd
Dec 8, 2011 7:44 pm
... MaxIm DL does not alter the data from the camera, except of course if you calibrate the image. If you are using dark frames and have a high pedestal ...
70279
Robert
rjhertel2001
Dec 9, 2011 12:06 am
The image was acquired in MaximDL, under Guide>Expose. I was trying to come up with a good target ADU for an automation program, and I noticed a lot of 1020...
70280
quicksandastro
Dec 9, 2011 10:34 pm
I have an AP130 with an AP Mach 1 mount. Once I align the mount to the north star, and I let the telescope drift for 5 min, I seem to get a drift of about 5 to...
70281
Ron Wodaski
rwodaski
Dec 9, 2011 10:42 pm
It really has to do with what will product satisfactory images for you. With careful work using the drift method, I've seen telescopes with a focal length...
70282
Bob
tekic545
Dec 10, 2011 6:17 am
Polar Align Max will get you very close to perfect alignment, in 2 or 3 iterations (doing only half the correction it prescribes in each iteration.) PAM is...
70283
Ken Harrison
ken4optics
Dec 11, 2011 3:43 am
As the brightness of the star increases I'm seeing not only the peak intensity increase but also the "wings" of the gaussian curve ( as the exposure captures...
70284
COR SIMONS
corkandra
Dec 11, 2011 3:44 am
Hi All an image I took an hour ago...dec.9th 5.30 AM. Cold hands but happy with the result(s) Here a first photo: ...
70285
COR SIMONS
corkandra
Dec 11, 2011 3:47 am
Hi here 2 more pics I took this early morning..the eclips hope you like them All the best Cor http://members.quicknet.nl/c.simons/planets6.htm ...
70286
Ken
ken4optics
Dec 11, 2011 4:01 pm
Using a CCD camera, each pixel records the photons and displays an ADU - the relationship between them being the gain of the camera. Every star image produced...
70287
Ken
ken4optics
Dec 11, 2011 4:01 pm
http://learn.hamamatsu.com/articles/ccdsatandblooming.html Saturation and blooming??? (The write up infers that the "overflow"; is dumped to "drain" not to the...
70288
Stan
stan_ccd
Dec 11, 2011 5:35 pm
... I'm not sure you understand the dynamics of PSF and FWHM. A constant FWHM will produce vastly different star disk "sizes" based only on brightness. As for...
70289
Stan
stan_ccd
Dec 11, 2011 6:31 pm
... BTW, that's not impossible. The worst seeing I ever measured was 6.5" (it was viscerally and obviously horible). Also, small short-focus scopes typically...
70290
Ken Harrison
ken4optics
Dec 11, 2011 7:34 pm
Stan, Obviously I have some understanding of the PSF/ FWHM and the relationships.... My basic question remains...if the total spread of the PSF is constrained ...
70291
Ron Wodaski
rwodaski
Dec 11, 2011 7:40 pm
It sounds to me like you are making an assumption about the width of the star image on the screen and the FWHM. There is NOT a linear relationship between...
70292
Stan
stan_ccd
Dec 11, 2011 7:55 pm
... That's also the impression I get. But maybe you have an image with wildly disparate FWHM? If so then post the linear FITS for examination. Stan...
70293
Ken Harrison
ken4optics
Dec 12, 2011 12:49 am
I'm not communicating well....sorry. I'll upload the original image, a x3 extract and the star profiles as measured in AstroArtV5. In the meantime - an...
