One of my goals in photometry has been to contribute to time sensitive alert notices. In the past year I have learned a great deal about photometry and have acquired capabilities in accurate LC generation of EP's & EB's, ToM studies, as well as learning how to use VPhot. I also have familiarity with AIJ, MPO Canopus, AIP4Win and other programs. But expertise is a long-way off!
But now I could use some advice on how to proceed to provide accurate observations for alerts such as #758 & #764.
Rather than learn from trial an error could others who have established observation programs share their work flow so that I can get started with accurate data? Or, if this is the incorrect forum, or there is a reference I have missed, please direct me and I will take appropriate action.
Thanks in advance for sharing your experience and expertise.
John
My apologies for the duplication of this post.
Hi John,
Alert Notice 764 gives a pretty good description of the desired observation:
V-band
positive detection
S/N of at least 20
Can you explain a bit more about what kind of advice you are looking for? There are no bad questions!
Arne
What I am…
Thanks Arne,
What I am looking for is how to get from the initial observations (say 5 images of the target, calibrated & registered, & average stacked) to the extended file format entry in WebObs? I see that there are a number of programs listed in WebObs that will create the AAVSO extended file format. Which are veteran observers using and how?
For example: I looked at the VPhot (which is listed) guide and the only reference to extended file format is in 3.5 Time Series Tools, not single magnitude measurements. I see in AIP4Win there is a Magnitude Measurement Tool that will create the extended file format. Is that what people are using?
In a nutshell, I thought I was ready to do this but now I am confused how to get from A to Z, what programs and tools within those programs are being used by experienced observers from the initial observation to the data submission.
Perhaps I am overcomplicating this?
John
DJCA
Good! Now I understand your issue. For just a single measurement, you need to display the image, and identify target, comp and check stars as per the manual. Then on the left hand side is a button for "view photometry report". If you have defined a sequence and identified a target, that button will do a single-image photometry report. You can then export that as an extended format file and submit to webobs.
For time series, you go back to the home page and select time series.
So I think you just missed the report button. I hope that helps!
Arne
Sounds too easy! Just to be sure: these steps are in VPhot correct?
Thanks again,
John
yeah, it really is easy. I've summarized it a bit, so you should look at the VPHOT manual, and I'd suggest looking at Ken Menzies' video tutorials as well, but I bet you can figure out this beginning photometry stuff without looking at the manuals. Once the observation is submitted to the AID, you can always delete and replace if you find that you did something wrong.
Arne
Videos: Could you please share the title(s) of the videos you are referring to? I see many on the AAVSO web page, but don't see anything referring to Ken Mezies. I do see a video tutorial: "Introduction to Astronomical Photometry using VPhot" by Christopher Duston. Which I found by searching YouTube for: vphot.
Thanks again for your advice Arne.
John
John:
It is not that difficult to learn VPhot. If you read the VPhot Guide and just play around a little you will figure things out. You will learn a lot this way. Reading/trying/experimenting is the best way to learn!
Click on the Support link in the upper right hand corner of VPhot Images List, and you will find the video tutorials Arne mentioned. BTW, I did not create them! They are out of date but the basic procedures are covered.
Ken Menzies
John:
If you read the CCD Photometry Guide (Page 23), you will find a list of software that is used for differential photometry. Many/most of them produce an aavso extended format report for submittal to webobs. Have you reviewed this document yet?
If you search for 'photometry software' in the search box on the aavso main web page, you will find many forum posts that may help with your decision.
Ken
Thank you for your…
Ken,
Thank you for your advice, I have looked at the tutorials in VPhot , was looking for them in AAVSO. Also the tutorial I mentioned previously was informative.
Yes, I have the CCD Photometry guide and have been using AIJ and MPO Canopus for differential photometry. I'm getting better with AIJ, as I go through the tutorials and have signed up for the advanced class next month. But for the most part my intent is to use AIJ for LC's. Most of my work to date have been light curves, mostly of overcontact binary systems, and a couple of EP transits. My LC's of the binary systems and SPP's have matched those in the data archive very well.
I have been practicing with VPhot and am getting close. Was just now trying to create a report and upload to WebObs. The images are of a standard field I observed as I worked to create my transforms. What I need to do is focus on VPhot, make and report some observations, and keep with it until it becomes familiar.
I am thinking that for the Alert magnitude observations it will be easier to use VPhot to create my reports in the extended file format. Would you agree?
John
DJCA
John:
If you have taught yourself how to conduct photometry of a time series with AIJ, you have more than adequate skills to do the same in VPhot or other software! You have used the term light curve (LC) analysis because I assume you were more interested in the times of minimum of the variable or exoplanet than the standard magnitude. You were conducting a time series analysis of many images followed by an extrema (max/min) calculation.
BTW, VPhot can be used for time series and single image photometry. Vphot also gives you a standard magnitude photometry report in the proper format (AAVSO extended report format) for submittal with AAVSO WebObs. As you know, AIJ does not generate an AAVSO report without some external modification with some generally unknown tools.
So yes, VPhot is a simple, intuitive software for conducting photometric analysis and generating appropriate AAVSO standard magnitude reports from one or many images.
Ken
PS: LesvePhotometry, Maxim and AIP4Win will also do this.
Thanks for the compliment Ken. But I must add that I didn't learn all this by myself, as I had a great deal of assistance from my mentor Kevin Alton. We have worked together for quite some time now and I have been able to contribute data to two papers he recently published in JAAVSO. Of course he did all the analysis, but I learned a great deal along the way.
Yes you are correct, time series analysis. I'm still learning the terminology.
No, I wasn't aware AIJ wasn't capable of creating the AAVSO report format, thanks for saving me the time looking for it. I am making progress creating single image standard magnitude reports and uploading them into WebObs. Haven't quite got it right but it won't take much longer.
Thanks again to you and Arne, having this level of support is greatly appreciated,
John
Arne & Ken:
Finally weather and available time coincided to allow me to make some test observations and practice the process. I chosed two long-term variables that had recent observations to compare. My observations were within .043M of the last two observations (averaged).
Just wanted to thank you for your assistance and encouragement.
John