Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Survey of M31 Globular Clusters using WFPC2 on board HST   We report new, as yet unpublished HST/WFPC2 V, I photometry of 9 globular
clusters in M31. These are part of a total sample of 19 clusters on M31 with
well observed CMDs from HST. The clusters have the full range of horizontal
branch morphologies from blue HB to red clump, but none are found with an
extreme (blue only) horizontal branch. Plots of HB type vs [Fe/H] are similar
to those of Galactic clusters, including a hint of second parameter clusters.
Sixteen halo fields adjacent to the observed clusters included in our images
have been analysed. The M31 halo metallicity distribution peaks at [Fe/H]=--0.7
with a tail toward low metallicity, resembling the halo of NGC 5128; metal rich
giants appear to be centrally concentrated.

34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci