Subject: Re: [sloan-25mlog 4797] Re: 2.5m obslog 20191124 (SJD 58812)
From: Karen Kinemuchi
Date: Mon, 25 Nov 2019 14:24:14 -0700
I guess I=E2=80=99m having a hard time seeing what these lurches are.  =
Without a snapshot on the axis error plot, I=E2=80=99m not sure what =
I=E2=80=99m looking for.  =46rom your screen shots of the guider images, =
something like the guide stars looking elongated is hard to catch, =
especially if seeing worsens and the guide stars aren=E2=80=99t as =
clear.
I guess the obvious case would be if the guide stars in the acquisition =
fibers clearly move around and leave trails or are distorted due to =
sudden moves.  It seems to me the guider has been doing a good job =
correcting (no obvious overshooting, for example), at least that=E2=80=99s=
 what I saw last night.
> On Nov 25, 2019, at 10:22 AM, Daniel Oravetz  =
wrote:
>=20
> Thanks for noting the directions along with timestamps, that's very
> helpful. I think in last night's cases, what looked like lurches were
> actually normal instances of changing dither positions between MaNGA
> exposures. The time stamps noted coincide with the timing between =
MaNGA
> dithers changing. Before the guider actually centers on a =
newly-commanded
> decenter/dither position, it looks a lot like a lurch. The fact that =
the
> directions noted were in +/- dec also make sense given the ditherPos =
was N
> and/or S in the reported instance.
>=20
> Dan
>=20
>> * A couple of lurches were caught this evening.  See log for time =
stamps.
>=20
>> Possible lurch seen at 5:55Z.  Move in dec. gimg-0758 appears to =
coincide
>> with this movement.
>=20
>> 05:55:25  boss exposure  900.0, file=3D301682, N
>=20
>> Possible lurch at 10:15Z, 11:05Z in Dec (negative).
>>=20
>> 11:40Z  Thin clouds coming in.
>>=20
>> MANGA DATA:
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> 10:16:41  boss exposure  900.0, file=3D301714, S
>> 11:05:54  boss exposure  900.0, file=3D301717, S
>=20
>=20
>=20
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