The planetary nebula NGC2438 has a series of faint shells surrounding the bright inner portion of the PN. We are testing the feasibility of observing these shells in Ha and OIII. Ground-based images suggest that these shells may have small-scale features that will be resolved with HST.

This proposal takes short and long dithered exposures in H-alpha and OIII to image the faint outer shells of NGC 2438. Shorter exposures in NII and SII will also be taken. The exposures are to test the viability of observing these faint structures as part of the SM4 ERO observations. Extrapolation from ground-based images suggests it might be feasible if there is structure that is unresolved in the ground-based images. 0 false 0.0 0.0 false false false false false SUPPORTED ISM SHELL PLANETARY NEBULA This object was generated by the targetselector and retrieved from the SIMBAD database. Modified to agree with coordinates published by Brian Skiff, Lowell observatory. Small changes. J2000 00 00 0.0000 +00 00 0.00 J2000 POS-TARG DITHER 0.3535 LINE false false 2 45.0 WFPC2-LINE 1 false The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11827 :visit-id "01" :proposal-version -1 :trans-version "20080624" :date "15-Aug-2008 08:37:45.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 537792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11827 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11827 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2720 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3137 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11827 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2720 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3137 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11827 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3137 :pcs-gap 0 ) false 3 0