Standard stars recommended for HIRES and ESI V RA ( 2000 ) Dec Type 11.8 G191B2B 05 05 30.6 +52 49 54 DAO [GOOD] 11.2 Feige 34 10 39 36.7 +43 06 10 DO [GOOD] 11.8 Feige 67 12 41 51.8 +17 31 20 sdO [GOOD] 10.5 BD+28 4211 21 51 11.1 +28 51 52 Op [GOOD] 11.8 Feige 110 23 19 58.4 -05 09 56 DOp [GOOD] Standard stars NOT recommended for HIRES and ESI (due to strong absorption lines) 10.5 Feige 66 12 37 23.6 +25 04 00 sdO [BAD] 11.7 HZ 44 13 23 35.4 +36 08 00 sdO [BAD] 12.8 Grw+705824 13 38 51.8 +70 17 08 DA3 [BAD] 10.8 BD+33 2642 15 51 59.9 +32 56 55 B2 IV [BAD] For HIRES, a 300 second exposure is appropriate for an 11th magnitude standard star, depending on the slit width, seeing, and wavelength range of your setup. For ESI, a 200 second exposure (for V=11.0) should work ok, depending on slit width and seeing.