Proposal #575

Proposer	(2046) Franz-Josef (Josch) Hambsch (hambsch@telenet.be) obscode: HMB
Assigned To	(3663) Dirk Terrell
Date Submitted	Nov. 6, 2024
Status	Allocated
Priority	Normal
Proposal	The name of the source is LS I +61°302. This stellar binary object is detected across the electromagnetic spectrum into the TeV regime. It is also included in the search for neutrinos. Periodic signals have been detected in its emission with at least three period values: 26.5 d, 26.9 d, 1667 d. These three periods are related via a beating. In particular the long history of radio observations has shown that this beating phenomenon has remained stable for the past 45 years [1]. In order for any timing analysis to be able to resolve the two close periods 25.5 and 25.9 days, it is absolutely necessary to have a light curve with a sufficiently high sampling rate and - most importantly - a long enough time series. The length of the light curve has to be more than ~5 years. It would be great to have continued monitoring at optical wavelengths. In particular, it is known that the long-term modulation, resulting from the beating of 25.5 d and 25.9 d, has systematic phase-shifts across the electromagnetic spectrum [2]. Unfortunately, when I did this investigation, the situation in the optical regime did not allow me to determine the long-term phase, leaving this data point vacant in my Fig. 2. It would be an immediate science case to fill this gap in order to better understand the physical processes behind this phenomenon. [1] https://ui.adsabs.harvard.edu/abs/2024A%26A...683A.228J/abstract [2] https://ui.adsabs.harvard.edu/abs/2021Univ....7..245J/abstract Daily observations would of course be fantastic. However, given the shortest periods in question (~26.5 d), such a high cadence is not a strict requirement. The most important is a continuous monitoring without larger gaps. Simultaneous monitoring in multiple filters in order to investigate the SED in the time domain would be of great interest. Based on this e-mail of the PI F. Jaron, I request observation of the target in BVI filters if possible on a daily basis. Regards, F.-J. (Josch) Hambsch

Targets
Target	RA (H.HH)	Dec (D.DD)	Magnitude	Telescope	Observation Frequency	Expiration Date	Proprietary Term
ZALD J02391806+6119252	2.655017	61.32367	10.7–10.9	BSM_NH2	1	May 14, 2025	6 Months

Comments

(4726) Kenneth Menzies — Nov. 15, 2024, 7:07 p.m.

committed to NH

(2046) Franz-Josef (Josch) Hambsch — Nov. 17, 2024, 3:28 p.m.

Hi Ken, I have reduced the images provides for ZALD J02391806+6119252. I see that the exposure times in B and V could be reduced by a factor 2 (60 sec and 30 sec, respectively for B and V band). I-Band exposures are Okay.

(4726) Kenneth Menzies — Nov. 18, 2024, 3:37 a.m.

Exposures changed.

(2046) Franz-Josef (Josch) Hambsch — Nov. 29, 2024, 3:30 p.m.

Hi Ken,
any new observations of my target? Since more than 10 days, I did not receive any e-mail concerning new images.

(4726) Kenneth Menzies — Nov. 30, 2024, 4:08 p.m.

I put it on NM also.

(2046) Franz-Josef (Josch) Hambsch — Dec. 3, 2024, 8:09 p.m.

Thank you. I got images from last night from NH2 and NM. Hopefully weather in NM is better than in NH.

(2046) Franz-Josef (Josch) Hambsch — Dec. 15, 2024, 2:55 p.m.

Hi Ken,
airmasses on the NM images from last night were between 4.1 and 3.9, hence the target was too early observed. Please try to stay below airmass 2 if possible. Thank you.

(4726) Kenneth Menzies — Dec. 16, 2024, 12:56 p.m.

Josch:

The plan uses an airmass limit of 2 so something is incorrect. I assume all the other images you have received had a reasonable airmass?

Ken

(2046) Franz-Josef (Josch) Hambsch — Dec. 16, 2024, 1:35 p.m.

Ken, indeed so far all other images had a good airmass.

(4726) Kenneth Menzies — Dec. 17, 2024, 5:07 p.m.

Josch:

Trying to find a cause.

Is the expected target present in the image? IOW, is the scope pointing correctly? If the target is present, is the image time consistent with the airmass/altitude?

(2046) Franz-Josef (Josch) Hambsch — Dec. 17, 2024, 7:17 p.m.

Target was in image and the time was consistent (I assume) with the airmass/altitude. Lesve gave good calculations, except that the airmass was large and getting smaller with the last image in the series.

Comments on this proposal are closed.