PixInsight Forum

PixInsight => Image Processing Challenges => Topic started by: dayers on 2012 April 01 14:16:34

Title: NGC 8310 challenge
Post by: dayers on 2012 April 01 14:16:34
Hello all,

The University of Arizona Public Outreach program is offering remote access (for a price) to their 0.81 meter, f/7 telescope located at their SkyCenter observatory on top of Mt. Lemmon at 2,791 meters. Control is by means of a scripted plan I write for the SkyCenter's ACP Observatory Control Software. I gave it a shot on a couple of nights of good seeing on 23 and 24 March. The target was NGC 3810, a pretty little galaxy in Leo. I have uploaded a dozen or so of those frames to PixInsight Files for anyone who would like to play with the data.

I am currently trying to create a master flat to use with the supplied bias and dark masters to properly calibrate and integrate the handful of red frames I uploaded. So far I'm not coming up with what looks like the right result. If I wanted to, I'm sure I could do the job in CCDStack, but I haven't yet found the key for doing the same in PI. Anyone want to take a crack at it?

You can access my files at endor.pixinsight.org with username=Temporary and password=Challenge3810.

Dave
Title: Re: NGC 8310 challenge
Post by: vicent_peris on 2012 April 02 01:02:05
Hi Dave,

Just downloaded some of the data and I've seen two problems:


- The dark has a gradients coming from up and downwards. They could be stray light if the dark has been done during the day. This affects the calibrated image.

- The bias image (generated by CCDStack) is not well written. See that it has a median level of about 0.12 ... The median dark level is about 0.02 . This bias cannot be used to calibrate this data set.


Regards,
Vicent.
Title: Re: NGC 8310 challenge
Post by: Juan Conejero on 2012 April 02 12:15:25
Quote
The bias image (generated by CCDStack) is not well written. See that it has a median level of about 0.12

The bias is a 32-bit floating point image that seems to store numbers in the 16-bit range. It can be loaded correctly by setting the 0 - 65535 floating point input range in the FITS Format Preferences dialog box. Loaded this way, it has a median value of 0.0197, which seems plausible.
Title: Re: NGC 8310 challenge
Post by: Juan Conejero on 2012 April 02 12:17:18
Question: do you have the individual bias and dark frames (the 16-bit raw frames)? It would be nice if we could generate the masters in PixInsight.
Title: Re: NGC 8310 challenge
Post by: dayers on 2012 April 02 14:39:21
Hi Juan,

First, where do I find the FITS Format Preferences dialog?

I will see if the individual bias and dark frames are still available. If they are, I can probably get them. I would love to be able to generate the masters in PI.

Dave
Title: Re: NGC 8310 challenge
Post by: georg.viehoever on 2012 April 03 01:32:24
First, where do I find the FITS Format Preferences dialog?
Look into the "Format explorer", left hand side where you also find the console.
Title: Re: NGC 8310 challenge
Post by: dayers on 2012 April 03 06:23:18
I found that, Georg, but can't find a dialog. Format Explorer > FITS. Is anything displayed there editable?

Dave
Title: Re: NGC 8310 challenge
Post by: dayers on 2012 April 03 09:02:04
Never mind - I found the Edit Preferences button... later.
Title: Re: NGC 8310 challenge
Post by: georg.viehoever on 2012 April 03 09:22:13
Never mind - I found the Edit Preferences button... later.
:D