UIST: Engineering - blockers for IJ and JH grisms

History:

• Aug 2006: Realised JH (and maybe IJ) need blocking filters.

NIGHTTIME CHECK ON POSSIBLE BLOCKER FOR IJ GRISM.

2006-08-29: Took flat/arc/standard obs of BS6975 (A3V, 6.57mag) with the IJ grism and the PK50 and J-spectral blockers. Peaked up spectra after acquisition (wouldn't need UPICK correction with J-spectral). Comparison spectra are shown below.

NOTE: The J-spectral blocker cuts off at 0.96 micron, so arc lines seen below this wavelength are missing in the J-spectral data because of the filter. Otherwise, both sets of data look very similar; maybe a 2nd-order arc line at 1.40um that shouldn't be there.... Throughput may be worse with J-spectral.

NIGHTTIME COMPARISON OF IJ WITH SHORT-J AND LONG-J

2006-09-01: Took flat/arc/standard/source data on WR140, a Wolf-Rayet star will lots of broad, strong line emission. Data taken through the IJ grism, again using PK50 and the J-spectral filter as a blocker. We also took data through the short-J and long-J grisms. In all four data sets the various bumps and features match well. There is no evidence of additional lines coming through in 2nd order...

Orac-DR reduced spectra of WR140. Again the IJ data are plotted in red (PK50) and blue (J-spectral). The long-J and short-J spectra are plotted in green (both use the J-spectral blocker).