AAVSO: American Association of Variable Star Observers

Proposal #162

Proposer (34230) Christopher Colvin (christopher.colvin.1992@gmail.com) obscode: CCHC
Assigned To(3663) Dirk Terrell
Date SubmittedNov. 11, 2020

Good evening,

I am writing to propose that I receive some telescope time from BSM NM for a proprietary star that isn't a known variable of any type.

I have data from my schools telescope from when we were observing Exoplanet XO-2N b.
One of the members of our analysis team clicked on another star as a comparison and shockingly a light curve appeared that was even deeper than the XO-2 system.
When we looked at other stars in the image under the assumption that this was an equipment error or atmospheric effect, this was not the case.
ASAS-SN data is fairly sparse and not fine enough detail to pick out what is likely a very short period exoplanet.
TESS Sector 20 data does show a dip in the light curve, but it is after a downlink and needs both verification and or validation from an outside source.
Data on this star (TYC 3413-242-1) is very sparse and no quality light curves with the cadence we need are available.

I request that I get a time series in V band measurements for a period of one month.
The requested cadence would be 25 to 50 observations spread evenly across every hour of the night as long as telescope time is available.
Reasoning behind the measurements is to attempt to find the exact period of this potential exoplanet in order to get better observations.

We would be using our schools telescope for this, but it is down for maintenance issues and it's proving difficult to get someone in to work on it due to COVID.
The team is very eager to get follow up data on this and I hope that as a long time AAVSO member and AAVSO ambassador that the AAVSOnet could help me out here.

Thank you for your time and consideration.

-Chris Colvin

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
TYC 3413-242-1 7.772488 50.38122 11.34–11.36 SRO May 31, 2021 1 Year


(3663) Dirk Terrell — Nov. 13, 2020, 10:48 a.m.

From Arne:
The main concern I have with this proposal is the large amount of telescope time requested. If we had a rough ephemeris and could schedule the observations, I'd say go for it. But taking essentially half nights for 30 nights seems excessive. Maybe run this for 2-3 nights and see if the desired precision is reached? Can't they get a rough period from ASAS-SN or their data and TESS?

(34230) Christopher Colvin — Nov. 13, 2020, 11:03 a.m.

I realized this was a big ask and decided to get a rough period estimate even before you had requested them. Please see below:

We are thinking 28 days and no longer an exoplanet but likely a binary system.
TESS, ASAS-SN and our data all line up to roughly a 28 day period.

The next opportunity is going to be around December 11th. So if we could run from the 10th to the 13th, would that be acceptable?

Thank you,


(34230) Christopher Colvin — Nov. 13, 2020, 11:06 a.m.

Clarification: December 10th - 13th.

Thank you.

(3663) Dirk Terrell — Nov. 13, 2020, 4:42 p.m.

Approved for the nights of Dec 10-13. BSM_TX is recommended.

(34230) Christopher Colvin — Nov. 13, 2020, 6:30 p.m.

BSM TX is acceptable. Thank you for the quick turnaround!

(4726) Kenneth Menzies — Nov. 17, 2020, 4:25 p.m.

Chris, please describe this more specifically: <<The requested cadence would be 25 to 50 observations spread evenly across every hour of the night as long as telescope time is available.>>

(34230) Christopher Colvin — Nov. 17, 2020, 10:38 p.m.

Hi Ken,

For the cadence, if I could get V band imagery of my target five times per hour at a 12 minute interval for the duration of each night, that would be preferable.
If a secondary cadence plan is required, please observe my target three times per hour at a 20 minute interval.

(4726) Kenneth Menzies — Dec. 2, 2020, 1:48 p.m.

Committed to TX for 4 nights.

IMHO, this is a waste of resources to try to see an EB with depth of 0.02 mags! Best to wait until TESS takes some more images.

(34230) Christopher Colvin — Dec. 10, 2020, 2:13 p.m.

Hi Ken,

ASAS-SN data shows the star that is being observed to have greater variation than 0.02 mag.
The quoted magnitude is from non-proprietary data.

Thank you,


Comments on this proposal are closed.