Proposal #296

Proposer	(18738) James Clem (jlclem@gcc.edu) obscode: CJAD
Assigned To	(3663) Dirk Terrell
Date Submitted	Dec. 6, 2022
Status	Allocated
Priority	Normal
Proposal	We request observing time to conduct timeseries photometry of 5 blue metal-poor stars (BMPs) that are potentially variable. Our project focuses on discovering variable stars among the BMP population and determining their pulsation periods, since most of the published research concerning BMPs has been focused on determining composition, with variability being largely ignored. We intend to expand variable star research into the BMP population and begin a catalog of BMP variables to be used by future projects. Our target stars were selectively chosen from unpublished data collected by the late Dr. Arlo Landolt. From these data we have identified several BMPs that exhibit strong signs of variability. However, we do not have enough clear data for these stars to conclusively determine that they are indeed variables or to calculate their pulsation periods accurately. We therefore request timeseries photometry in the Johnson V-filter of the 5 candidate BMPs listed below. For each star, we have estimated the observing time required to capture a full period. We understand that timeseries photometry is discouraged by AAVSOnet, so if these durations are not feasible for one night, we propose instead observing for only 1-2 hours per night over several nights. These observations can be made during non-photometric and/or bad seeing conditions as long as the exposure times are adjusted appropriately. Additionally, we can make use of bright time (i.e., moon illumination >50%) provided the target is greater than 30 degrees away from the moon. Finally, due to the faintness of our targets, we request the observations be taken with Faint Star Monitors.

Targets
Target	RA (H.HH)	Dec (D.DD)	Magnitude	Telescope	Observation Frequency	Expiration Date	Proprietary Term
BPS CS 22174-040	1.477920	-7.40118	13.2	OC61	1	June 11, 2023	1 Year
BPS CS 22185-009	3.248278	-14.72944	13.8	OC61	1	June 11, 2023	1 Year
BPS CS 29509-027	0.837714	-30.99894	12.5	OC61	1	June 11, 2023	1 Year
BPS CS 29518-024	1.286699	-32.44941	14.5	OC61	1	June 11, 2023	1 Year
BPS CS 29527-038	0.629079	-20.13642	14.5	OC61	1	June 11, 2023	1 Year

Comments

(18738) James Clem — Dec. 6, 2022, 3:24 p.m.

Please see part 2 of this proposal for 2 additional targets.

(4726) Kenneth Menzies — Dec. 8, 2022, 5:50 p.m.

James,

You stated "We therefore request timeseries photometry in the Johnson V-filter of the 5 candidate BMPs listed below. For each star, we have estimated the observing time required to capture a full period. We understand that timeseries photometry is discouraged by AAVSOnet, so if these durations are not feasible for one night, we propose instead observing for only 1-2 hours per night over several nights."

Did you include the 'estimated observing time' somewhere? What am I missing?

(18738) James Clem — Dec. 8, 2022, 6:38 p.m.

Ken,

We intentionally did not include exposure times for two reasons: 1) I recall reading somewhere on AAVSOnet pages that exposure times shouldn't be specified in the proposal but rather estimated by the telescope curator on the night the observations are taken (I can't seem to find where it says that again, though), and 2) I omitted exposure times to make our time-series observations more attractive to the TAC (since time-series is discouraged) and more easy to fit into a schedule for a 1-2 hour block of time per night rather than saying "we need 6+ continuous hours of observations with an exposure time of xx seconds"

If you feel it necessary to provide a basic estimate of exposure time length for each target, along with an overall duration for observations, then we can certainly do that.

I hope that is clear enough of an explanation!

James

(4726) Kenneth Menzies — Dec. 9, 2022, 2:37 p.m.

James:

1. Yes, don't worry about exposure time. I use magnitude to estimate the exposure. Of course, if you can live with a lower SNR (<100?), that is good to know.
2. What would be the imaging duration to get a full period? You just mentioned 6+ hours. Is your estimate that each would require more (or less?) than one full night to cover the period? That helps decide whether to image for one entire night or many partial nights. You do have five targets to deal with!
3. IOW, what alternative/compromise works best for your analysis and aavsonet? Thus, my interest in the extra info so we an make am 'optimum' decision.

Ken

(3000) Sebastián Otero — Dec. 12, 2022, 7:27 p.m.

James,

since these objects are not in VSX, when it's time to submit your results to the AID, you will have to submit them to VSX first.
I checked the first one and it is a Gaia DR3 variable, so maybe there are other similar cases. The Gaia DR3 information (name, reference, discovery credit) will have to be incorporated to the submission. We plan to add the Gaia DR3 variables to VSX, but that is a long-term project and you may want to submit these ones sooner.

Information on Gaia DR3 discoveries:

https://www.aavso.org/gaia-dr3-variables

Information on how to submit objects to VSX:

https://www.aavso.org/vsx-do-it-yourself-0

https://www.aavso.org/vsx/_images/Manual.pdf
https://www.aavso.org/vsx/index.php?view=about.faq
https://www.aavso.org/vsx/index.php?view=about.notice

Cheers,
Sebastian

(4726) Kenneth Menzies — Dec. 13, 2022, 7:13 p.m.

Committed to OC61. Plan runs each target with V filter on one full night at highest priority. This test will identify any potential problems.

(18738) James Clem — Dec. 15, 2022, 9:41 p.m.

Ken:

My apologies, I've been knee-deep in administering and grading final exams... thus, my delayed response!

Answers to your points below:

1) Ideally, we'd like to have as high SNR as possible while at the same time keeping exposure times short for proper cadence in the observations.

2) As part of the proposal my students wrote up - they provided a duration to get what is the suspected period for each of the targets. These are provided in the final column below:

Target RA (hr) Dec (deg) V Observation Time (hr)
------------------------------------------------------------------------------------------------------------------------------
BPS CS 22174-040 1.477920358 -7.401175917 13.20 4.8
BPS CS 22185-009 3.248277778 -14.72944444 13.80 2.6
BPS CS 29509-027 0.837713736 -30.99894245 12.50 4.8
BPS CS 29518-024 1.286698592 -32.44940537 14.50 2.4
BPS CS 29527-038 0.629079096 -20.13641835 14.40 7.92

3) Ideally, we'd like to get enough continuous time coverage of each star over a decent time-span to nail down the fundamental pulsation period. Moreover, we'd like to sample these on multiple nights to find evidence of (possible) multiple pulsation frequencies. Keep in mind, these are likely pulsating with multiple modes - hence, observations scattered across future nights might be needed to nail down both short- and long-term periods.

I hope those answer your questions - please don't hesitate to ask more.

James

(18738) James Clem — Dec. 15, 2022, 9:48 p.m.

Sebastian,

Understood... thanks for the heads up!

James

(18738) James Clem — Feb. 2, 2023, 3:23 p.m.

Has there been any progress on observing our targets? The five we listed above are no longer observable. Should we update our observing list to include more targets that are better positioned in the coming months? Or submit an entirely new proposal?

Comments on this proposal are closed.