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Which software to use?

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avdhoeven's picture
Which software to use?

Currently I'm working on some variable data and I'm looking at the results that I get. I used Maximdl, MPO canopus and the Vphot.

Vphot looks nice, but uploading big amounts of data is not working for me and the results seem not to be what I expect all the time. Somehow I have the best experience with MaximDl until now, but you can only do simple photometry without any corrections.

I was wondering what the more experience photometrists use and what they would recommend to use? MPO Canopus is quite complicated (which I don't mind) but I'm looking for some good tutorials... Any recommendations would be welcome....

TCB168's picture

I use a selection of software but mostly AIP4WIN. It is very popular with lots of AAVSO contributors.

I output both raw data and AAVSO upload versions.  It is then easy to average results etc in a spreadsheet and modify the already created upload format in a text editor.

I also use MIRA but motly just for preprocessing.


Terry (BHQ)

WBY's picture
Photometry Software

 I have only fiddled with Canopus a couple of times and that was a few years ago. Therefore it would be hard for me to compare others to it. 

I also found Maxim DL to be very limited particularly since you must have a comparison star to use the photometry tool and the information window aperture tool is not very accurate and is not recommended for photometry. You can't get raw magnitudes, at least I found no way to get them and for certain things like establishing transformation coefficients you don't want to do differential photometry. You want the raw magnitudes.  

Many people use AIP4WIN. I have used it in the past and it's pretty good and readily available as freeware. More than 5 years ago I tried a number of different packages and decided I liked Mira-pro the best. It was developed by Michael Newberry,  one of the original developers of IRAF. It has robust GUI interfaced algorithms for photometry and other image analysis tasks - including source extractor -  and one of the slickest image calibration pipelines I have ever seen. The problem is it is expensive - on the order of Maxim DL or a bit more if you get the scripting add-ons. This was developed as a Windows program but I think it is also available for the current MAC OS. 

Of course there is IRAF itself or the version integrated with Python, PYRAF. If you found Canopus too complicated you will find these ridiculously so. IRAF, however is regarded as the gold standard of Image Reduction and Analysis (Facility) software for astronomy. It is versatile, has lots of add-on packages to do almost anything you can imagine, has a image viewing interface called DS9 that is incredibly versatile but it has a very difficult learning curve. There is also a free package called image J. It was developed for medical imaging photometry as were many of the best photometry packages including Mira-Pro (because that is where the money is). Image J is quite a good package BUT the last time I looked it did not have a conversion into magnitudes. You had to do that as a manual step at the end. It has some very interesting and helpful features, however and it is free. 

Finally, I have used VPhot and have not had unexpected results. It seems to work well. I don't know if there is a version that you can download to your computer. You could in its original implementation as Photometrica and perhaps it still can be. that would be an interesting question to ask on the forum. I don't see a post on that topic. I agree Uploading images to VPhot is a problem. It was bad enough with my old ST7 that was about 0.8 Mbyte per image. With my new camera at 16 Mbyte per image, it is essentially impossible for more than a very few images over my DSL connection at 0.7Mbps. If you have 10 Mbps it might not be such a pain. It would be great if there were a VPhot client that ran on user computers to do all the heavy lifting on the image with automated interfaces to AAVSO for Variable star search comp stars, and reporting. That could also greatly reduce the storage and traffic on AAVSO servers. I am not competent to evaluate the complexity of such a development project, however. 

I am sure that I haven't scratched the surface of all the photometry packages that are out there. There are probably a whole bunch I have never heard of or have forgotten about. 

Brad Walter


Perhaps I should be specific about the meaning I apply to "raw magnitude" what I mean is precisely


So it is a negative number, or if you offset all measurements by the same sufficiently large constant you can make them positive i.e. -2.5*LOG(Netcounts*GAIN/EXPTIME) + 25

So not only is it not transformed, it isn't referenced to a comparison star magnitude.

I use the term "instrumental magnitude" for a magnitude that is referenced to a comparison or standard star magnitude but which is not transformed.
Tmag_raw - Cmag_raw + Cmag_sequence 

A Confusing Vocabulary:
The terms raw, instrumental  standard, differential and absolute are not uniformly used and can have conflicting meanings in different contexts or different meanings in the same context when used by different people.  It leads to confusion. The term standard as used in the MTYPE field of WebObs, for example is a bit of a misnomer although it is completely explained in the link in the notes, if you read that far. I would only use the term standard to apply to the magnitude of a recognized standard star. I wouldn't even use it to describe a magnitude that had been transformed to a standard magnitude scale. I would use "transformed" to describe that. I don't even use "standard" to describe the chart magnitude of a comparison star. I use "sequence" magnitude or "reference" magnitude to describe comp star magnitudes (unless they are recognized standard stars) because most sequence star magnitudes are only transformed to a standard magnitude scale. They are not sufficiently measured to qualify as a photometric standard stars. 

I certainly would never use the term "absolute" magnitude to mean anything other than a magnitude transformed to a recognized standard and adjusted for distance and interstellar extinction to an observational distance of 10 parsecs (see 2.3.3 in Binney and Merrifield, for example)  but you sometimes see it used to mean an instrumental magnitude, 
Tmag_raw -Cmag_raw + Cmag_sequence,

to distinguish it from a differential magnitude,  
Tmag_raw - Cmag_raw.

To add to the confusion, either of these two magnitude types are most frequently produced by AAVSO members using differential photometry vs. all-sky photometry. So differential photometry does not necessarily result in a differential magnitude, but it can. It just depends on which formula you use.

Some of these distinctions are only the vocabulary choices of one journeyman amateur, but I think they make distinctions much clearer, particularly trying to explain things to someone new to photometry. 

Bikeman's picture
>  Many people use AIP4WIN. I

>  Many people use AIP4WIN. I have used it in the past and it's pretty good and readily available as freeware. 

AIP4WIN is not freware, you need to buy the book "Handbook of Astronomical Image Processing" to get the software. Around 100 bucks. If you find AIP4WIN as a "free download" somewhere, it must be an illegal copy.

A package that hasn't been mentioned yet is IRIS (which is freeware). It it nice for image calibration and basic photometry, but doesn't offer "batch" photometry features like AIP4WIN, AFAIK. Idt does have a little scripting feature build-in, tho. 

If you are working on photometry of very crowded fields, SourceExtractor (under Linux) might be an option for source identification and photometry. Anyway, anybody not afraid of Linux and configuration-rich Pro tools can try the "SciSoft" package from ESO, a compilation of pro tools which has IRAF, SourceExtractor and a ton of other tools bundled together. 





Photometry software

I hope Brad meant that IRAF was readily available as freeware although anything is possible. 

AIP4WIN is a commecial package authored by James Brunell and Richard Berry and sold  for about $100.   In my view it is an excellent program and for your 100 bucks you also get an excellent book that every imager should have on their book shelves.  Used by many AAVSO observers.  I have used it from time to time.  There is a limit on the number of computers that you can load AIP on.

I generaly  do long time series and primarily use MaxIm because it is a very robust program that provides a lot of useful support like PinPoint and stacking.  You can get raw data from it but it takes some fiddling.  I always import my nights data into Excel for plotting, further analysis and  checking.  I have  also written some crude and rude scripts so I can edit the AAVSO output file if I need to. I use MaxIm when I want to calculate my transform coefficients but it has been awhile :(

I don't think MaxIm would be useful for all sky photometry but works fine for differential photometry.

Finally there is a fairly new free-ware program available....LesvePhotometry.  It has some interesting features and resembles VPHOT in some ways.  It, in theory, will do a very large number of images without running into memory problems.  It is very fast to use.  I've had some problems with it and am not using it.  But a number of high volume observers are using it and are very happy.  I believe it requires a full PinPoint license.  You can find out about it at

Hope this helps.

Jim Jones, JJI

WBY's picture


Thanks, I stand corrected about AIP4WIN. I have just seen so many free copies running around on the internet and on CDs that I assumed you no longer had to buy it. 

IRAF, PyRAF and Image J are freeware. I have downloaded all from the official sites for free. PyRAF is supported by the Space Telescope Science Institute. 


WBY's picture
Transform Coefficient using Maxim


My curiosity. How do you use Maxim DL to get transform coefficients? I ran into the problem that it requires a comp star to get magnitudes and that introduces bias due to color differences between whatever comp star you pick and the target stars. It is true that I wasn't using the latest Maxim DL. Has this limitation changed, did I overlook a feature of Maxim, or maybe I am being overly precise. 

I have always imaged one of the standard clusters over a wide range of airmasses, calculated raw magnitudes [-2.5*LOG(netcounts*GAIN/EXPTIME)] of all of the standard stars, calculated extinctions for each star individually and adjusted the individual stellar magnitudes to extra atmospheric raw magnitude. After that I run the regressions [e.g. (V-vo) values  vs (B_V) values and analogous regressions for the color indices] to come up with the transformation coefficients. 

I never could figure out how to get raw magnitudes as defined above out of Maxim DL. 

Do you have an easier way?


Brad Walter

Hi Brad I did a lot of

Hi Brad

I did a lot of fooling around with this a few years back.  And working from memory, you can always compensate for the color of the star you use as a comp star but it turns out that it doesn't make any difference.  You are only interested in the slope of the equation (V-inst) = a(v) +b(v)*(B-V).  Changes in B-V of the comp will move the line up and down (change a(v)) but not change the slope (b(v)).  I basically follow the method outlined in Arne's M67 paper.

I don't worry about extinction since my FOV is about 15'x22'.

I'm not trying to sell anyone on using MaxIm.  It has some strong points and some weak points.  One of the issues associated with MaxIm is that it can't run the photometry tool in it's batch mode.  That means that you are limited to the number of images that you can process at any one time.  Another is that it doesn't really take advantage of available core in 64 bit systems which is a further limit on the number of images you can process at the same time.  This probably isn't a problem unless you are processing long time series.  In general terms I am limited to something around 180 ST 8 images in 1x1 and maybe 400+ in 2x2 mode.

Jim Jones


Jim Jones

WBY's picture
Maxim & Transformation Coefficients

Jim, I think I am concerned about something different than the issues in your response. This is getting off the topic of this thread so I started a new thread. The thread topic is obvious. I may be concerned about nothing, or I may be all wet. Then again, it might be something worth thinking about. 


GFB's picture
Photometry software

There's no silver bullet amongst these packages, they all seem to have their strengths and weaknesses.

AIP4Win has always been the easiest to understand, for me, particailly because of the book which is very well done.  There' s a number of things it doesn't seem to do and for me it's the most fragile, it crashes a lot.

I agree with Brad that Mira is a gold standard for the photometry.  The user interface has not kept up with other packages with regard to processing for AAVSO, so the ease of use is behind.

Canopus has some very cool tools.  The PhotoRed side of the program has a AAVSO Batch processing tool with excellent features for grabbing and loading comp stars, processing several targets in one run and a built in database that stores the observations.   You then have a records of what and when you've looked at things, and a way to retrieve the observations if need be.

I haven't used IRAF but have seen it demonstrated a few times.  It's clear it has powerful tools.  It's also clear it's not only not 'user friendly', it's 'user oblivious'.  I tell myself someday I'll have to 'bite the bullet' and learn it too.


Bill Goff

MJB's picture

AIP4Win is apparently popular, perhaps being an early and inexpensive entrant.  However, set up and data entry are tedious to say the least.  The program invites errors, and if your pointing is not fairly precise between images or you cross the meridian it is difficult to get through a large stack of image without upset.  Even having learned its idiosyncrasies I still find the program a pain to work with.


Is a wonderfully straight forward shareware program with lots of capability but it does not do AAVSO style reports or Std. Magnitudes, only instrumental. 

I normally use:

This is also a shareware program and it runs circles around AIP.  Drawback is you have to have a pinpoint license costing $200, but as AIP is half that anyway, there is no contest in my mind.

Data entry and set up are a fraction of the effort as with AIP and almost devoid of error potential, especially if you use the separately available tool that allows importation of data from the AAVSO website.

Once the sequence is established, you enter the index name you assigned to the star, click “go” and highlight the images in your file and off it goes.  Using pinpoint to find the relevant stars, Lesve automatically processes the images, generating all manner of data in real time as it does so. 

It can generate four different report styles (including AAVSO) and an error report where needed.  It will filter out images based upon preset parameters, such as image elongation, maximum ADU count, minimum SNR.

I have found one star our of nearly a hundred I have gathered data on over the last three months that it can’t resolve.  I suspect some adjustment would overcome this but I just have not focused on it. 

Current short comings, it does not include excluded images for violating the preset parameters in the error report, and I wish the optional excel report include the reference star’s instrumental magnitude reading instead of its stated magnitude.  However, these are minor issues that perhaps will be addressed in the future as the owner has been pretty good about upgrading the program.

sgor's picture
Which Photometry Software

I have been using AIP4Win for years and MJB is accurate in his comments about data entry. Much of this can be alleviated with PhotomCap

 MJB mentions LesvePhotometry. I am going to look into it, but at first glance it doesnt seem to generate HJD values which are important to several astronomers I work with.



MJB's picture
Photometry Software

Sgor, I agree that PhotomCap is a big help and similar in operation to what Lesve uses for that purpose, but my experience is the PhotomCap is sometime tempermental and more importantly, even when using PhotomCap, actually setting the comp stars is still a pain and fraught with potential error in AIP.  In Lesve, the available sequence stars are listed right there on the index page and you select or deselect them in an obvious and straightforward way. 

I can't claim familiarity but my impression is that when HJD is important, instrumental magnitudes are the likely end point and the other program I mentioned does HJD and processes image in an automated manner like lesve without requiring pinpoint. Be nice if the Muni people would add Std. mags and AAVSO reports as a feature. Pierre on the otherhand might be pursuaded to add HJD (if it is not now available, I am not where I can check at the moment) and instrumental magnitudes if asked and there was sufficient demand.  As it is I use both depending on my endpoint requirements. 

WBY's picture

Mira Pro 7 has a 1 click output to the Standard Extended format. I end up not being able to use it much of the time however because I am doing mutlicolor photometry in say VBBV, or IRVBBVRI blocks (or binned multiples of these blocks) and I am averaging the measurements in each color so that the resulting midpoint times of the averaged images in the various colors are as close to the same as possible. I could stack and average the images themselves and then do the photometry but I don't. I do the photometry on the individual images and average the results in a spreadsheet so the feature doesn't help. I do use it, however, if I am doing single color photometry.

Attached is a sample output CSV file from Mira-Pro 7 using an ensemble of comp stars. If you don't plate solve the images before doing photomtry the X and column values are the same and the Y and row values are the same. 

One of the things I shold have mentioned about Mira Pro is tht it has excellent documentation even compared to Maxim DL, which I think is darned good,  and much better than The Sky.  It is a real commercial product not a hobby project. I don't get commissions for recommending Mira I just like it, but, as I mentioned, "it ain't cheap." 

Brad Walter

Mira Pro for exoplanet differential photometry

Hi Brad, I am just a beginner with photometry.  I just ran my first photometry run with Maxim DL and a CCD camera.  That's about all I know now.  Nevertheless, I want to do some extremely accurate differential photometry on exoplanets.  Would you recommend Mira Pro for that purpose?  If so, what level of Mira Pro should I buy?  Are there any add-ons to Mira-Pro that I should also get?  One more question.. Is using Maxim DL ok for obtaining the original photos that I would later input into Mira-Pro?  Maxim DL is the software I am familiar with.  Thanks.



avdhoeven's picture
Lots of info

Everybody thanks for the replies! I didn't hear about Lesve and as I have pinpoint it sounds interesting, so I will give it a try...

dpp's picture
HJD in LesvePhotometry

I will add an option in LesvePhotometry to report the HJD instead of JD. The next release will be available in one or two weeks.

Pierre de Ponthiere

MJB's picture

Pierre, you have been so responsive to requests and suggestions I hate to ask for more but it would be most appreciated and I think a general improvement if instrumental magnitude could be added to the excel report for the referrence star.  It is already there for the check star.  Idealy, it would be good to have instrumental and stated magnitudes for both of these stars and add a R-CK for both the instrumental magnitude results and the stated magnitude and then chart the results for R-CK for the instrumental results.  This way one can quickly compare the difference between the nominal R-CK and the actual results for R-CK on each reading - the most basic QC check.  Thanks for your gift to the cause. 

sgor's picture
Lesve Photometry

Greetings, Pierre

I spent this morning becoming familiar with LesvePhotometry and to you I say, "Bravo and thank you!". And thank you for ur plans to include HJD. I must admit I spent  most of my time this morning trying to find the generated report files! Once I found them I thought, "Well of course, that makes sense.". I would like to request an option to enter a different folder for the report destination. 

Again, thank you for the lovely software.

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