Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Observing >> Variable Star Observing and Radio Astronomy

Pages: 1 | 2 | 3 | (show all)
rutherfordt
sage
*****

Reged: 05/07/06

Loc: Northeast Tennessee USA
Re: photometry questions new [Re: ASTERON]
      #4317701 - 01/16/11 09:15 AM

Asteron:

Concerning your equipment, one of the nice things about photometry is that the image quality is not as critical as if you taking a "pretty picture." It doesn't matter if your star images are smeared out over a few pixels (in fact, that is what you want-- you don't want the image of a star to be so tightly focused and tracked that its light falls onto a single pixel).

Go ahead and try what you have, you may be surprised at how well it does. I have a friend who carries a C14 with on his Atlas and it does really well-- it is a visual only set up, but I'm really impressed with how well it works.

Tom


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: rutherfordt]
      #4317748 - 01/16/11 09:47 AM

Tom,
Thanks for this comment. I didn't know that you can do photometry with less well focused images. That seems very interesting.
I have used my 12"LX200R to visually observe with my Atlas and it works real fine (if there is no wind). So I already know that the Atlas can take the weight. What I did not know was that you do not need perfect tracking for photometery.
I have a (non-cooled) Meade DSI IIPro CCD camera. Do you Think I can use it for photometry ? I have no way of controlling its temperature so any temperature changes during an observing session may change the pixel response to light. (however, I may be able to build a Temperature regulating enclosure for it).
If it is not usable - what would be a good starting level CCD camera for work with the 12" LX200R F/10 on an Atlas something which can yield Science grade S/N levels and can be gotten used for a reasonable price.

Edited by ASTERON (01/16/11 09:49 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: Hubert]
      #4317777 - 01/16/11 10:01 AM

Hubert,
Thanks, this is great. I also have an Explore Scientific 127ED triplet refractor (5"). I may give it a try on the Atlas.
Now all I have to do is get me a decent Camera.
By the Way, If you are going to be using a DSLR, How are you going to get the data for the relevant pixels from the Raw File ? can you actually know the light intensity from the Raw file, or are you going to be visually comparing it to comparison or calibration stars visually from the ficture ?
How would you know that the CCD of the DSLR does not heat up during use ? and how are you going to deal with pixel sensitivity changes during the night.
I have a Canon 40D - thats why I am interested to know how you are going to do photometry with a DSLR - because if it is possible, then I already have all the equipment that I need for starting.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: ASTERON]
      #4317789 - 01/16/11 10:06 AM

Hubert and Tom,
Is there a single high level text for photometry that can be used by a newbie but is very concise and at the same time practical ? I have no problem with graduate level math and I am not afraid of technical language and/or equations.
What should i buy or download ?
Thanks


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mirzam
Post Laureate
*****

Reged: 04/01/08

Loc: Lovettsville, VA
Re: photometry questions new [Re: ASTERON]
      #4317817 - 01/16/11 10:20 AM

I don't know about concise (the book is over 2" thick) but this contains chapters on photometry as well as software that is widely used.

http://www.willbell.com/aip/index.htm

I would be interested in others responses to this question as well.

JimC


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: Mirzam]
      #4318190 - 01/16/11 01:36 PM

Hi Jim,
Thanks for the link. looks like an interesting one ( especially as it includes the software as well). Do you know when the book was first published ? (I have some books from Willman-Bell that while being very good for their time are a little antedated because they dont cover the most recent stuff on the market.)
I am still interested in in other responses by other variable star obdservers.

Edited by ASTERON (01/16/11 01:37 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
gavinm
Carpal Tunnel


Reged: 08/26/05

Loc: Auckland New Zealand
Re: photometry questions new [Re: ASTERON]
      #4318418 - 01/16/11 03:27 PM

You could do exoplanets - short period, there's plenty of them, they aren't too challenging (although it is challenging to get really good data). I image from the middle of a urban environment using a range of filters. LP has not been an issue.

Try this book by Bruce Gary (exoplanet specific but v/ good)
http://brucegary.net/book_EOA/x.htm

This one is also quite good.
http://observatory.ou.edu/wrccd22oct06.pdf


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mirzam
Post Laureate
*****

Reged: 04/01/08

Loc: Lovettsville, VA
Re: photometry questions new [Re: ASTERON]
      #4318569 - 01/16/11 04:45 PM

Hello Asteron,

I know what you mean about some of the W-B titles being out of date.

However, the Image Processing handbook is the second edition from 2005. I have the 3rd printing of the book from 2009, and the AIP4WIN software included with it is version 2.3.1, which is fairly recent (I think).

The book includes a good discussion of many basic principles of image calibration, signal-to-noise, characterizing your CCD performance, etc., that are applicable to both astrophotography and photometry. I like it but I still have a lot to learn.

JimC


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: gavinm]
      #4318588 - 01/16/11 04:53 PM

Hi Gavin,
Thanks for the links.
Exoplanets are interesting - I will look into this


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: ASTERON]
      #4318593 - 01/16/11 04:56 PM

Jim,
Thanks. I will probably order it directly from W-B
too bad they rip you off on international shipping rates.


Post Extras: Print Post   Remind Me!   Notify Moderator  
btieman
scholastic sledgehammer


Reged: 07/24/08

Re: photometry questions new [Re: ASTERON]
      #4318813 - 01/16/11 06:55 PM

You might also look up Brian Warner's book "Lightcurve Photometry and Analysis" Covers most topics relating to general photometry--variables, binaries, asteroids, etc...

I got my copy direct from: http://www.minorplanetobserver.com/ but I image Amazon carries it as well.

Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: btieman]
      #4319710 - 01/17/11 03:20 AM

Brian,
Thanks - looks like a very useful one I will order this soon.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: ASTERON]
      #4319722 - 01/17/11 03:48 AM

Brian,
Just ordered Brian warner's book from Amazon.
Supposed to reach me only on mid February
In the meantime I will try reading the PDF books recommended by Gavin (already downloaded).
Thanks everybody for the links and recommendations
Any other intresting primers or more advanced references or books ?

Edited by ASTERON (01/17/11 03:49 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Hubert
sage


Reged: 09/26/06

Loc: Belgium
Re: photometry questions new [Re: ASTERON]
      #4319823 - 01/17/11 07:16 AM

Hi Asteron,

Have you read the AAVSO CCD manual?

http://www.aavso.org/sites/default/files/CCD_Manual_2010_revised.pdf

clear skies, Hubert
http://www.vvs.be/wg/wvs/


Post Extras: Print Post   Remind Me!   Notify Moderator  
ASTERON
Carpal Tunnel
*****

Reged: 11/24/07

Loc: ISRAEL
Re: photometry questions new [Re: Hubert]
      #4319843 - 01/17/11 07:43 AM

Hubert,
No - thanks for pointing this out. I will read it.
Incidentally I thought in order to use AAVSO website you need to be a member ?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Hubert
sage


Reged: 09/26/06

Loc: Belgium
Re: photometry questions new [Re: ASTERON]
      #4319856 - 01/17/11 07:57 AM

No, you don't have to be a member.

clear skies, Hubert


Post Extras: Print Post   Remind Me!   Notify Moderator  
zvaragabor
member


Reged: 01/25/11

Re: photometry questions new [Re: Hubert]
      #6265821 - 12/21/13 06:16 PM

My question is, can I use a color webcamera for photometry?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: photometry questions new [Re: zvaragabor]
      #6266041 - 12/21/13 09:03 PM

I used to think that one needed a mono ccd and filters. Not so. Google "webcam photometry." Here is one paper I found, there are others.

http://adsabs.harvard.edu/abs/2009SASS...28..117T

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
jgraham
Postmaster
*****

Reged: 12/02/04

Loc: Miami Valley Astronomical Soci...
Re: photometry questions [Re: Ed Wiley]
      #6266095 - 12/21/13 09:56 PM

I don't see why not. I would use the green channel and the V photometric reference data. The usual guidelines apply in that you either need to operate within the linear range of the camera or determine the transfer function to linearize the data. One possible challenge in that a webcam might be limited to 8 bit data. Whenever I start using a new camera for photometry I'll take some time to compare my results with data reported on the AAVSO web site.

Give it a try, what could possibly go wrong?


Post Extras: Print Post   Remind Me!   Notify Moderator  
zvaragabor
member


Reged: 01/25/11

Re: photometry questions new [Re: jgraham]
      #6273682 - 12/26/13 01:45 PM

Can I convert G (RGB) to V (UBVR)?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | (show all)


Extra information
0 registered and 2 anonymous users are browsing this forum.

Moderator:  Rich (RLTYS) 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 4997

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics