Proposal #115

Proposer	(19714) Tõnis Eenmäe (tonis@obs.ee) obscode: ETOA
Assigned To	(3663) Dirk Terrell
Date Submitted	Sept. 10, 2019
Status	Accepted
Priority	Normal
Proposal	TESS satellite will be observing stars V509 Cas, rho Cas and 6 Cas in sectors 16, 17, and 18. However, it is measuring just brightness variations in a very broad red filter. Those well known yellow hypergiant stars (6 Cas is a suspected one) are variable in several/many time-scales starting from few days. While community of amateur astronomers are obtaining remarkably high quality photometry of those bright stars, most of the measurements are done using green channel of DSLR cameras, typically in a non-transformed way. To obtain information about surface temperature of those stars and how it changes (crucial for interpreting high-resolution spectra) during those variations, transformed B,V,I photometry would be very much needed. I'm asking for photometric monitoring of those stars from 11. September (starting time of sector 16) till 1. December 2019 (ending time of sector 18) to support an on-going high-resolution spectroscopic monitoring campaign of those stars. For all of those three stars, an ideal observational cadence would be about 2 observations per week, 1 observation per week is still useful. I would like to ask for cadence of 3-5 days and target signal-to-noise ratio that corresponds to 0.01 magnitudes. With best wishes, Tõnis Eenmäe tonis.eenmae@ut.ee

Targets
Target	RA (H.HH)	Dec (D.DD)	Magnitude	Telescope	Observation Frequency	Expiration Date	Proprietary Term
V509 Cas	23.001417	56.94528	5.0–5.2	—	—	—	6 Months
rho Cas	23.906389	57.49939	4.5–4.7	—	—	—	6 Months
6 Cas	23.813944	62.21450	5.3–5.5	—	—	—	6 Months

Comments

(19714) Tõnis Eenmäe — Sept. 10, 2019, 8:07 a.m.

When I wrote that proposal, I was thinking of using AAVSO BSM telescopes.

(3663) Dirk Terrell — Sept. 10, 2019, 3:53 p.m.

Arne suggests adding the SU filter.

(19714) Tõnis Eenmäe — Sept. 10, 2019, 6:57 p.m.

Yes, this is a great idea!

(2911) Michael Nicholas — Sept. 10, 2019, 7:18 p.m.

Will need feedback on exposures. - Mike N.
BSM_NM:
#Created 2019-09-19 nmi
# $Id: AAVSO_P115_ETOA_AUTO.csv 832 2019-09-10 23:14:04Z NMI $
#USERNAME=AAVSO
#PROPOSAL=115
#REQUESTER=ETOA vphot
#target priority monitor maxX nrepeat bin [filter exposure nexp]
V509_Cas 60 2 2.5 1 1 SU 3 6 B 2 8 V 1 15 I 0.7 15
rho_Cas 60 2 2.5 1 1 SU 3 6 B 2 8 V 1 15 I 1.7 15
6_Cas 60 2 2.5 1 1 SU 3 6 B 2 8 V 1 15 I 2.7 15

BSM_NH2:
#Created 2019-09-19 nmi
# $Id: AAVSO_P115_ETOA_AUTO.csv 831 2019-09-10 23:12:36Z NMI $
#USERNAME=AAVSO
#PROPOSAL=115
#REQUESTER=ETOA vphot
#target priority monitor maxX nrepeat bin [filter exposure nexp]
V509_Cas 60 2 2.5 1 2 SU 2.25 6 B 1.5 10 V 0.75 20 I 0.525 30
rho_Cas 60 2 2.5 1 2 SU 2.25 6 B 1.5 10 V 0.75 20 I 0.525 30
6_Cas 60 2 2.5 1 2 SU 2.25 6 B 1.5 10 V 0.75 20 I 0.525 30

(19714) Tõnis Eenmäe — Sept. 11, 2019, 4:54 a.m.

I guess if those exposure times are known to be good for such brightness ranges, everything should be fine. The only question is somewhat higher scintillation in blue filters. Perhaps for BSM_NH2 SU filter, total exposure time could consist of 8 frames, to give same total exposure time as in B?
Because V509 Cas is a bit fainter than rho Cas, at least same exposure could be used (i.e. 1.7x15 instead of 0.7x15).
Tõnis

(19714) Tõnis Eenmäe — Sept. 25, 2019, 10:06 a.m.

It seems that there is some kind of problem accessing files via ftp.aavsonet.aavso.org server. It was possible last week but not now. Do you have any information or ideas about that? My AAVSO username is tonisee.

(19714) Tõnis Eenmäe — Sept. 25, 2019, 10:31 a.m.

I'm asking and answering by myself. I figured out, that I can access that site is by anonymous FTP.

(19714) Tõnis Eenmäe — May 15, 2020, 10:31 a.m.

I got an e-mail from aavsonet where I was asked to estimate the exposure times of BSM_TX observations. I got 6 Cas and V509 Cas frames taken in B filter. Comments are:

6 Cas is very close to saturation, max ADU is ~60000. Exposure time is 1.5 seconds. Taking into account that Cassiopeaia is currently close to lower culmination, exposures at smaller airmass would be even more affected. For 6 Cas in B-filter, I'd ask rather slight de-focusing (FWHM is ~1.6 pix) and keeping the exposure same.

I have the same comments about V509 Cas in B-filter, too. Target itself is clearly overexposed in single 1.5 second exposure. FWHM of the stellar image was 1.4 pix. Probably slight de-focusing is better than reducing exposure time.

Comments on this proposal are closed.