I am new to this. I have captured successfully some eclipsing binaries using my SeeStar S50 using photometry. I would like to do more long period variables, as well as eclipsing variables, etc. I have rather polluted skies, at Bortle 7-8 and also limited visibility due to a number of trees. I do have good areas to observe from roughly 45-220 degrees from my front yard, and some availability to the NE from my back yard. Due to saturation of the sensor in my SeeStar, I am limited on the bright end at approximately a magnitude of 8, and on the dim end, about a magnitude of 13 or so, depending on exposure. How do I proceed it finding the appropriate variables to examine?
He who would scan the figured skies Their brightest gems to tell Must first direct his mind’s eye north And learn the Bear’s stars well. https://www.aavso.org/vsots_zuma
Firstly, I would recommend to use short exposures images stacking for avoiding of saturation and for dynamic range extension. Well as, my modest experience shows that program should be short, but observations should be systematic. Objects with high brightness range are preferable - for example UMa miras R, T, S etc, very interesting RCB type variables such as Z UMi and chaotic young UXORs. I suppose, Seestar may reliably detect extremums of short periods bright eclipsing and pulsating variables, if there are comparison stars in the FOV.
BTW, there are sucsessful asteroid occultations registrations with Seestar, so do not forget about this scientifically important area of amateur astronomy.
I’m also looking into using the SeeStar for photometry, so I’d love to hear more about your setup. Are you using the ZWO app for control, or do you have another system in place? Also, is your SeeStar EQ-mounted?
One of the biggest hurdles for newcomers to photometry is developing a meaningful observing program. It can help to connect with a mentor or join an organized observing campaign to guide your efforts.
I coordinate one such program focused on flare stars, called the Red Dwarf Group. We’re a mix of amateur and professional astronomers working together on a long-term observing campaign. If you’re interested in learning more or getting involved, check out this thread on the AAVSO forums for all the details:
Regarding my set up, it is strictly the alt/az SeeStar S50. I plan to set up the SeeStar in EQ mode - I just haven’t had the time, but I have all the necessary parts to do so. I have installed ALP but have not used it. I use the phone app for control (for now).
One issue that I have run into regarding the phone app, is that to enter the RA & DEC, the app requires an Epoch of JNow, instead of J2000. So I have to do a conversion. There are conversions available online, or I use Stellarium when it can find the object.
I would like to use the planning feature, but at the moment I need to print a drop-off dew shield so that when the battery runs down and goes into auto-shutoff, it will preserve the gears.
That said, I have had some excellent results with my SeeStar on some short period variables, like BE Lyn, VV UMa, and AE UMa. I have found (like others) that the SeeStar saturates at about a magnitude of 8, and in my skies for up to stacks of 4 minutes (24 x 10-sec subs), that my limiting magnitude is about 13-14 depending on the sky condition.
I use ASTAP for data reduction.
Personally, I am thinking about purchasing another SeeStar S50 so I can focus on both astrophotography and variable star observing.
Thanks, Scott, for your reply. It sounds like you’re using the ZWO app successfully, but Seesstar_alp will give you far more control over your imaging run. I have my Seestar up on a wedge and have attempted to use seestar_alp; however, I’ve encountered a few issues I need to look into. I recommend getting seestar_alp to work in AZ mode before trying it with EQ mode. Let’s stay in touch; I’d love to hear how your photometry is going with this device.
That is what I was planning to do - is to use ALP in alt/az mode first, then work up to EQ mode. My personal email is kb0fhp@gmail.com - I can send you some of the results that I have been able to obtain to date.
Substantial information and advice about selecting targets can be accessed from the panel labeled “Tools and Observer Resources” on the AAVSO Homepage. Also, the AAVSO Target Tool at https://targettool.aavso.org/ lists stars according to their (constantly updated) current priority. The AAVSO page describing their legacy long period variable program is at AAVSO Legacy LPV Program | aavso. More such resources are available, but these sites might be the easiest next steps to take.
I have used an 8in SCT for most of my measurements on stars in the 10 - 11th mag range. Most of the RDG are currently observing AD Leo - a somewhat brighter star. I’m using a 51mm WO refractor for this star. I’m also setting up a Seestar 50 to see how it performs.
From my experience, 10-11 magnitude is not a problem, but you need to stack the images at least 12 x 10-sec subs to get a decent SNR. My skies are pretty bright.
Scott, it is recommended to use 30-sec cadence for RD monitoring.
Well, 2 min is possible too (I myself tried 1-1.5 min for Bond’s star with AAVSOnet MPO, and even detected ~2B flare), but 30 sec is obviously better
I’ve added 3 nights of observations of AD Leo to the AID using a Seestar. About 1,200 observations at 30s cadence. It seems to work OK, errors in the range of 0.005 to 0.05.
Hi Andrew, that’s great. Are you using your Seestar in AZ/EL of EQ mode? Also, are you using the ZWO app or seestar_alp? I’ll check your data out on the AID.
I am also trying to do photometry with a Seestar S50 via ASTAP and wanted to ask about your process. Do you import the individual FITS into ASTAP, extract green channel, identify the star of interest and a few others (i.e. comp & check) in one image and hit the start button or is there more to it? Also, when you stack subs for faint stars (13-14 mag), is that manually or via a script/software?
Stack the files in a group average (done in ASAP - it is down a couple of lines when you right click to extract green channel). I usually stack in groups of multiples of 6. Obviously, the greater number of stacks, the greater the SNR.
Once stacked, I select Gaia V Database, and Online DB <13
I then select a stacked FIT to view and go to the main page to view. Once there, I view the image and select Variable Star Annotation. The image populates with the annotated variables.
I go back to the spreadsheet view and select “measure all annotated” in the measurement selection.
I then hit the forward key (like on a cassette player), and all the annotations in the image are measured.
Once measured, I scan through the list, and only report with an SNR greater than 50.
To create the report, I select “AAVSO Report”, and once that appears, I enter my observer code and select the “DSLR” in the drop-down box to the lower right. This is new, and in the update for 2025.02.25.
Now one issue that I seem to have, is that the report, if reporting GAIS DR3 stars, does not have the coordinates in it, and I have to populate those myself.
Realistically, I have found that for most of the stacks in my Bortle 6-7 area, I am limited to about 8-14 magnitude.
