Proposal #419
| Proposer | (18215) Brian Kloppenborg (bkloppenborg@aavso.org) obscode: KBKA |
|---|---|
| Assigned To | (3663) Dirk Terrell |
| Date Submitted | Sept. 12, 2023 |
| Status | Allocated |
| Priority | Normal |
| Proposal | I am requesting snapshot observations of 75 objects in support of the ARMADA (ARrangement for MIcro-Arcsecond Differential Astrometry) program at Georgia State University’s (GSU) Center for High Angular Resolution Astronomy (CHARA) interferometer and the European Southern Observatory’s (ESO) Very Large Telescope Interferometer (VLTI). This multi-year survey combines radial velocity, astrometric, and photometric data to create a comprehensive model of the binary systems. Initial results were published in Gartner et al. 2021 [1] and Gartner et al. 2022 [2]. Due to these systems being binaries that are occasionally closely spaced (0.2”), previous photometric surveys may split the stars into two separate measurements or have both stars combined into a single measurement. Our data request is to re-observe these stars at the current epoch and reduce the data with knowledge of the orbital phase and hence separation. A total of 3-5 epochs consisting of 5 observations of each star is requested. Note that these are not variable stars in the traditional sense, so their data will not be submitted to the AID. All observations must be complete by June 2024. Objects are included in a spreadsheet submitted directly to Ken Menzies. [1] https://ui.adsabs.harvard.edu/abs/2021AJ....161...40G/abstract |
| Target | RA (H.HH) | Dec (D.DD) | Magnitude | Telescope | Observation Frequency | Expiration Date | Proprietary Term |
|---|---|---|---|---|---|---|---|
| see_sheet | 0.000000 | 0.00000 | 0.0 | BSM_TX | — | March 24, 2024 | No |
Comments
- (4726) Kenneth Menzies — Sept. 12, 2023, 6:30 p.m.
I received the spreadsheet. Filters are BVR. Will probably be placed on BSM_TX and BSM_S if approved. All targets are bright stars so only short exposures needed. Targets cover entire sky, so nightly impact not too large? 3-5 separate runs per target needed.
- (4726) Kenneth Menzies — Sept. 15, 2023, 6:29 p.m.
Targets are:
gam_Gem
omi_And
alf_Del
eta_Vir
gam_CrB
lam_Lup
mu_Ori
kap_Peg
nu_Gem
mu_Cet
2_And
iot_Ser
zet_Boo_B
lam_Cyg
tau02_Hya
126_Tau
psi_Sgr
HD29573
psi_Cyg
64_Ori
97_Aqr
kap_Cnc
iot_Lyr
68_Gem
74_Psc_A
l_Ori
iot_Aps
26_Aur
eps_Equ
HD46273
25_Her
HD118889
HD1976
51_Tau
45_Aql
131_Tau
HD49643
HD64235
k_Vir
100_Her_A
HD31093
HD189340
lam_Cas
HD11031
HD127726
HD87822
HD87652
HD173093
53_Sgr
HD195206
HD43358
HD36058
HD153370
BD_11_1117
HD10453
HD128415
2_Cam
HD145589
HD31297
HD133484
HD196088
HD75974
HD114993
HD160935
HD48581
HD163346
HD154569
HD201038
HD38769
HD5143
HD224512
HD158140
HD16753
HD144892
HD137798- (3000) Sebastián Otero — Sept. 15, 2023, 8:27 p.m.
My question would be: do we know the current separation? Are we going to take this into account to plan the observations?
How much do the separations range? Do we know when are we going to observe a blend and when we aren't? Do the separations vary so much in time that at times they were solved and sometimes they weren't? What is the resolving power we have? At what separation can we say we are going to be able to solve a binary safely? At what separation will we need to use a larger photometric aperture to include both components completely? We need to be sure to get blended or solved magnitudes because intermediate values will be useless. If the separations vary we won't know what we will get. Let's keep discussing it to know more about the proper way to address this.- (18215) Brian Kloppenborg — Sept. 16, 2023, 2:29 p.m.
The ARMADA team believes that all objects will be sufficiently separated to be detectable. With that said, they desire for us to disclose information about our apertures and whether or not the objects are indeed clearly separated. The interferometers they are using yield flux ratios, so as long as we report either individual star photometry or combined star photometry as part of our observations the ARMADA team will be able to work with the data.
- (4726) Kenneth Menzies — Sept. 16, 2023, 5:18 p.m.
This is inconsistent with what I just emailed to the TAC committee. I understood that the binary components are now 0.2" - 0.5" apart? Normal seeing for our scopes is 1" - 4". Since I'm doing the photometry, I'm very confused now. :-(
Ken
- (18215) Brian Kloppenborg — Sept. 16, 2023, 5:20 p.m.
The components should be separated, but if they aren’t we just note that when we reduce the data. The ARMADA team just needs an unambiguous statement on whether the photometry is of individual components or both components.
- (18215) Brian Kloppenborg — Sept. 16, 2023, 5:41 p.m.
The objects in the proposal are all binary star systems. Some of the binaries are photometrically variable; however, most are not. The issue at hand is that the semi-major axis of these systems is large enough that the stars could be within or outside of a single photometric aperture depending on orbital phase. The ARMADA team claims that the catalogs they typically use do not specify the epoch, so they cannot discern if the quoted flux is for a single star or both stars at the same time. The ARMADA team needs this information because the optical interferometers they are using only provide flux ratios for the stars, not absolute flux for the entire system.
In this proposal, we are attempting to resolve that issue by obtaining data with high precision, clearly defined epochs, and explicitly specified apertures so that the ARMADA team can calibrate their data.
- (3663) Dirk Terrell — Sept. 25, 2023, 8:20 p.m.
Approved. Let's see how it goes.
- (4726) Kenneth Menzies — Sept. 26, 2023, 1:56 p.m.
Committed to BSM_S and BSM_NH.
Comments on this proposal are closed.