GCN Circular 1247

J. T. Lauroesch, D. G. York, C. Hastings, D. V. Bowen, D. Meyer, and
D. Q. Lamb report:

We obtained 75 minutes of integration (five 15-minute exposures) on
SN2002ap using the echelle spectrograph (ARCES) on the Apache Point
Observatory 3.5-meter telescope.  The spectra were taken with a 1.6
arcsecond wide slit, 3.2 arcsec long, in seeing of about 1.5 arcsec.
The spectra give complete spectral coverage from 3600 A to 10500A. The
signal to noise ratio (per pixel) is about 20 at Ca II and 50 at Na I.

These spectra, at a resolution of 8 km/s, show clear detections of
interstellar NaI and CaII in both the Milky Way and M74.  A  weak,
narrow, NaI feature (D1 and D2) is detected in M74 with a column
density of approximately 2.5e11, suggesting there may be little cold
interstellar gas in M74 in front of the SN.  Assuming the "typical"
Galactic relation between NaI and HI, this fact would suggest a total
hydrogen column of approximately 5e19 in M74 along this sightline.  Two
components are seen in M74 in CaII; one narrow, corresponding in
velocity to the NaI absorption noted above, and a second broader
component, approximately +25 km/sec with respect to the Na I feature.
The Ca II features each span roughly 50 km/sec, and are centered near
650 km/sec (heliocentric).  The Galactic Na I and Ca II lines are about
5 times stronger that their M74 counterparts in the SN spectrum.  This
object, while it is still bright, is ideal for measuring interstellar
abundances in the outer part of the M74 galaxy.

This sightline passes near the location of a known Galactic high
velocity H I cloud (Wakker 2001) at approximately -100 km/sec (LSR);
however, no absorption is detected at these velocities in either Ca II
or Na I to limits of 20 and 10 milli-Angstroms respectively.

No other significant narrow absorption or emission lines were seen in
the spectrum.

Further observations are in progress.