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Now that the COSTAR corrective optics have been installed and aligned in the Hubble Space Telescope (HST), the Goddard High Resolution Spectrograph (GHRS) can obtain clean spectra and images of stars in very crowded fields.
To demonstrate this restored capability, an Early Release Observation program to observe hot, luminous stars in the center of R136a (the central cluster of the 30 Doradus complex in the Large Magellanic Cloud) has been scheduled in early April. Through this program we will obtain a series of UV images through the Small Science Aperture (SSA) and Large Science Aperture (LSA) of the GHRS. The images will be taken with the N2 mirror and D2 detector (CsTe cathode on a ${\rm MgF_2}$ window) and thus will have a bandpass that extends from 1150 to 3200 \AA. The SSA images will consist of 13 x 13 pixels with a pixel spacing of 0\farcs027 pixel$^{-1}$. Each pixel covers a 0\farcs11 x 0\farcs11 area on the sky. Thus each image will cover the entire SSA (0\farcs22 x 0\farcs22). The SSA images will include one centered on the initial pointing (located between R136a1 and R136a2; separation = 0\farcs12), an image of R136a2, and an image of R136a5 (0\farcs18 from R136a2).
Two LSA images of the central region of R136 will be taken. The first, a 3 x 3 mosaic centered on R136a5, will consist of 22 x 22 pixels each, with a pixel spacing of 0\farcs11 pixel$^{-1}$. Together these images cover a 5\farcs22 x 5\farcs22 area. The second, will cover the central 1\farcs2 x 1\farcs2 with a pixel spacing of 0\farcs055 pixel$^{-1}$. These images will be examined to determine the true pointing for the spectra of R136a2 and R136a5, the imaging characteristics of the GHRS, and the UV brightnesses of all of the stars within the field.
In addition to these images, 3 WFPC-2 PC exposures will be obtained with the F336W filter. These images are 5, 10 and 20 seconds in duration. Photometry of the stars in these images will be compared with the GHRS UV photometry, as well as published WFPC photometry.
