AAVSO: American Association of Variable Star Observers

Proposal #415

Proposer (34444) Kristopher Hultner (krishultner.astro@hotmail.com) obscode: HCKA
Assigned To(3663) Dirk Terrell
Date SubmittedSept. 9, 2023

I'm beginning to learn photometry, so I don't want to observe an entire period of variability. I have no idea if it's best to have one image or a short sequence of images that would then be stacked, but I want the interval between either individual images or groups of images that should be stacked to be about two hours. This should give me a chance to see changes in a short time (one night, not weeks or months), but without also overwhelming me with a lot of data points to process while also learning processing. It might not be enough for my data to provide a light curve, but what data I do develop can be added to that from others. I'll leave the exact number of images to what can be scheduled and what those volunteers with much more experience than I think would still be useful.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
RR Lyr 19.424419 42.78436 8.14–7.17 BSM_TX 1 March 13, 2024 No


(3663) Dirk Terrell — Sept. 14, 2023, 3:30 p.m.

The TAC would like to have images taken with BVIc filters to enhance the scientific return. We would also like to see more coverage of the light curve. We won't obligate you to do more than you are asking for, but we feel that, in addition to adding scientific value to the observations, you will have more data to look at once you do get comfortable with the data processing procedure.

(34444) Kristopher Hultner — Sept. 14, 2023, 8:19 p.m.

Yes, I intend to increase the cadence once I'm comfortable with the processing. I just got paired with a mentor from the mentoring program, so hopefully I'll get assistance as to what the increased cadence should be, when that time comes.

(4726) Kenneth Menzies — Sept. 15, 2023, 6:22 p.m.

Committed to TX. Image about every 1.5 hours per night..

(34444) Kristopher Hultner — Sept. 27, 2023, 1:07 a.m.

Now that I've gotten some data to process, I think I can safely increase the cadence. Could the TAC suggest the cadence they'd like to see?

(3663) Dirk Terrell — Sept. 27, 2023, 2:57 p.m.

A general rule of thumb is that you want at least 100 points over the light curve and that would amount to every 5-10 minutes for RR Lyr. For light curves that don't change over time, you can phase observations from multiple cycles pretty well, so you don't have to sit on it very night. But if the light curve changes shape with time, obviously that won't work very well. RR Lyr shows the Blazhko effect, so its light curve does change with time, over about a 40-day period. In cases like that, it is best to obtain data over as short a time as possible. So, as a scientist, I would say observe it as rapidly as possible for as long as you can. As a telescope manager, juggling projects from dozens of people, that's harder to do. Ken has a better feel for how a given telescope is loaded, so I would trust his input on the best cadence.

(4726) Kenneth Menzies — Sept. 27, 2023, 4:03 p.m.

Time series pose problems for aavsonet because they use up a lot of time every night, which is contrary to our need to get lots of proposals run on any given night. We can consider a single time series proposal for this learning request. However, it would be best for you to identify a night/time interval during which a time of maximum can be imaged. Alternatively, you could ask for a spot image each night and just use data from a long period of time to fill in the phase plot light curve to calculate the period.

As a prototype of the class, RR Lyr obviously has lots of data and is quite well understood. Running many time series so you can learn how to conduct photometry is not a great use of the system. Our desire is to help obtain useful scientific data. You've already learned how to conduct photometry so gathering more data from a well studied star is not a great use of the aavsonet system.


(34444) Kristopher Hultner — Sept. 28, 2023, 12:48 a.m.

My inclination was toward gathering data over a longer period, avoiding a time series. But the initial response from the TAC was that they'd prefer more coverage of the light curve once I'd learned, but I didn't get a sense of what that would look like other than more frequent than my initial proposal. As to Dirk's comment, I favor the telescope manager hat over the scientist hat, which also factored into my initial cadence suggestion.

I didn't intend to stay with RR Lyr for long, maybe only a month or two (or one 40-day cycle that Dirk said RR Lyr exhibits; the first delivered images were from Sept. 24), since it is well studied, but I did want to get enough to see a change in my readings, getting at least a partial curve of personal data. I have another accepted proposal for SU UMa that is my first long term project, but that has not yet made any images available. If it would be better from a science standpoint, maybe I could find another of the type that is less well studied and switch to that, taking the longer period approach over something flirting with a time series. I'm still unsure of how to select appropriate targets, so I want to try, even if we decide to keep this proposal active instead of ending it and going to another target.

Thoughts on staying with RR Lyr for a 40-day cycle vs. finding another of the type that could be more scientifically meaningful and changing to that?

(34444) Kristopher Hultner — Sept. 28, 2023, 3:35 a.m.

IU Cas has just 1 observation in the AAVSO database (I think I'm getting a better hang of VSX), and is an RRAB type without the Blazhko effect, with a period greater than half a day. Would it be a good candidate for the long period spot image approach (I'm thinking twice a night rather than once)? If yes, I'll submit a proposal for that regardless of the decision on ending or continuing this one.

(3663) Dirk Terrell — Sept. 28, 2023, 3:12 p.m.

I'm not an RR Lyr guy, so I'm not familiar with IU Cas but if it doesn't show the Blazhko effect, then a few points per night over a longer term sounds like it would meet your needs and also be valuable for adding to the database. I don't see much in the literature about it, but I haven't dug into it too deeply. If it does turn out to show the Blazhko effect, then that would be an important thing to find out. If not, then you should be able to produce a good phased light curve. Both results would be good. So I support the switch to IU Cas.

(34444) Kristopher Hultner — Sept. 28, 2023, 7:22 p.m.

OK. I just submitted proposal 430 for IU Cas. Let's keep this one active until that is allocated, and then we can complete this one.

(34444) Kristopher Hultner — Oct. 1, 2023, 3:37 a.m.

Proposal 430 is now allocated. We can now consider this proposal complete.

Comments on this proposal are closed.