Jitter Trend Analysis
Date: 11 June 1999
The following illustrate the comparison of two methods used
to compute the offsets among WFPC2 exposures within a certain association.
The first method uses the jitter information to reconstruct the
average right ascension, declination and roll angle during each observation.
The offsets between any observation and the so-called association leader
are computed from the extracted mean RA, DEC and ROLL angle.
The second method uses a cross-correlation method (see the IRAF dither package).
The following plots show, for each each member within an association,
the difference of the two distances (in units of 0.1 arcsec)
vs. the start time of the exposures
(in units of an HST orbit, about 96 minutes).
The fact that the discrepancy of the two method increases with time,
is explained by a zero point drift of the jitter information.
- u2690301a.trend2:
(NGC4496A-FIELD )
- u26k4a01a.trend2:
(HI-LAT )
- u2781e01a.trend2:
(NGC3351 )
- u2781e01a_rightmost.trend2:
(NGC3351 )
- u2840201a.trend2:
(GAL-CLUS1322+3027-POS1 )
- u28v0101a.trend2:
(LEO-II )
- u2cw0108a.trend2:
(TUCANA )
- u2e70202a.trend2:
(ANDROMEDA-I )
- u2h10201a.trend2:
(PAL4-CENTER )
- u2hb0101a.trend2:
(GAL-034943-381027 )
- u2hn0301a.trend2:
(FIELD-034120+193441 )
- u2jc0101a.trend2:
(4C41.17 )
- u2nu0101a.trend2:
(NGC4639 )
- u2o30101a.trend2:
(NGC7331 )
- u2oj0101a.trend2:
(53W002 )
- u2ovbu01a.trend2:
(PAR )
- u2s73003a.trend2:
(NGC2541 )
- u2y40101a.trend2:
(47TUC-WDF )
- u31p0103a.trend2:
(HDF-123649+621346 )
- u31p0115a.trend2:
(HDF-123649+621346 )
- u31p0115a_rightmost.trend2:
(HDF-123649+621346 )
Alberto Micol [ST-ECF] & David Schade [CADC]