TCrB Instructions
Contents
PI & COIs
Gamma-ray:
PI: David Green (+49 151 57636472)
COIs: Rubén Lopez Coto, Julian Sitarek (phone in here, during the night call me from shift leader mobile phone)
Stellar Intensity Interferometry:
PI: Tarek Hassan (+34 680 26 02 66)
COIs: Alejo Cifuentes (+34 629 52 31 95) Juan Cortina (+34 646 357 376)
Source
Source: T CrB
Coordinates: RA = 15h 59m 30.16s, DEC = +25º 55' 12.61"
Wobble: Standard
Zenith angle: < 70 deg
HV settings: Standard / Interferometry / Reduced HV (if around full moon)
DT settings: Extragalactic / Moon
Stereo observations with LST-1
Instructions
This section describes the instructions for the first night of observations of T CrB. Unless otherwise stated by the PIs, these observations are broken into two parts: Gamma-ray and Stellar Intensity Interferometry (SII). After the first night, only gamma-ray observations are planned, except if you are told otherwise by the PIs.
If you receive an alert regarding the T CrB eruption during the night, please call the PIs as soon as possible (their phone numbers are listed at the top of this page). In the case that gamma-ray observations of T CrB are started due to the automatic (GRB) procedure, stop these observations and switch to SII as described below. Also, if the PIs are not available, please begin the SII observations and keep trying to contact them. Once the PIs are aware of the eruption, communication with them should go through the following Zoom room: https://mppmu.zoom-x.de/j/65181605135?pwd=eW9lQjhyd25yK3ovU1paQTY2ZG9OZz09.
Important: The automatic GRB procedure should be disabled when observing T CrB to prevent the automatic repointing to another eventual transient event.
Coordination with MAGIC
T CrB observations should be done together with MAGIC. For this purpose, the Shift Leader phone is in a Telegram group with the PIs and the MAGIC Shift Leader phone. Use this group and the aforementioned Zoom room to coordinate the wobble positions with MAGIC and communicate with the PIs.
Cadence of Observations
The cadence of observations for the first night will go as described below unless otherwise stated. Wobble positions should be coordinated with MAGIC.
- SII: First 40 minutes (ON mode)
- Gamma-ray: Next 40 minutes (standard W1 + W2)
- SII: Next 20 minutes (ON mode)
- Gamma-ray: Next 40 minutes (standard W3 + W4)
- SII: Next 20 minutes (ON mode)
- Gamma-ray: Next 40 minutes (standard W1 + W2)
- Repeat the 20/40 minute cycle until T CrB goes above a zenith angle of 70 deg or the night ends.
It may be the case that LST only does gamma-ray observations and, if so, they will follow the standard wobble scheme. In this case, the procedure described above should be slightly changed so that the wobbles used by MAGIC match those used by LST, as shown in the following table:
| LST | MAGIC |
|---|---|
| W0.40+000 | ON |
| W0.40+180 | ON |
| W0.40+090 | W0.40+090 |
| W0.40+270 | W0.40+270 |
| W0.40+000 | ON |
| W0.40+180 | W0.40+180 |
| W0.40+090 | W0.40+090 |
| W0.40+270 | ON |
| W0.40+000 | W0.40+000 |
| W0.40+180 | W0.40+180 |
| ... | ... |
There is also the chance that the initial 40-min SII observations will be shortened if T CrB is not detectable by SII. In that case, the 40-min gamma-ray observations will begin and the 20/40 cycle will follow. Instructions on how to determine whether T CrB has been detected by SII are given below, as well as the detailed steps to swap from SII to gamma-ray observations and the other way around.
Gamma-ray observations
Gamma-ray observations are straightforward, since the source should already be included in the Current Period catalog of TCU. Observations should take place jointly with MAGIC, so please be in contact with the MAGIC shifters to ensure that the wobbles match and the observations begin at the same time.
If we are lucky, we will observe the optical rise of the nova, which is expected to happen very quickly, at several magnitudes per hour. Be aware that T CrB will become very bright in the optical, with an expected peak V-band magnitude of ~ 2. This will turn off pixels around the source and may cause oscillations in the rates. If this is the case, continue observations normally and report in the ELOG any issues that you see.
From gamma-ray to SII observations
Below are the detailed steps to follow in order to swap from gamma-ray to SII observations. A more in-depth description of the SII observations can be found here.
SII observations
The procedure explained above will start the data-taking of 5-min interferometry runs that will be saved into the interferometry computer. In order to check the acquired data, follow the next steps:
From SII to gamma-ray observations
Below are the detailed steps to follow in order to swap from SII to gamma-ray observations.
