Question and Answer

Question ID

0055

Language

English

Assigned Member

Y. Uchida

Category

proposal

Name

M. Tsujimoto

Institute

ISAS/JAXA

Question

We are preparing an AO3 observing proposal. We plan to impose a
time constraint that requires observations without Earth occultation, in
order to increase the observing efficiency to approximately 80%. For
example, out of a total telescope time of 300 ks, about 240 ks would
be on-source exposure.

In this case, what value should be entered as the exposure time in
RPS? Should it be the actual on-source exposure of 240 ks, or the
value corresponding to the nominal efficiency of 45%, i.e., 135 ks?

My impression is that the former (240 ks) is appropriate. However, in
that case, the accumulated exposure time relative to the total
telescope time (which assumes the nominal 45% efficiency) would
appear inconsistent. Given that we are requesting a fairly long
observation, this might complicate the evaluation by the TAC.

I would appreciate your guidance on how this should be handled.

Thank you very much for your help.

Answer from

M. Tashiro

Institute

Saitama University

Answer

If it is a Time-Constrained observation, please specify the exposure time based on the expected efficiency during that period. For the example you provided, please use 240ks instead of 135ks.

Status

Accept 2026-02-09

Close 2026-02-10