Comet C/2015 G2 MASTER (formerly M503ujx) as seen from the SSO scopes at astronomical twilight in the morning, the large rectangle is the field of view of T12, the small that of T9. Also nearby are 88P/Howell and C/2013 US10 Catalina. Click to embiggen.
The presumed comet M503ujx has been confirmed as a comet and is now C/2015 G2 MASTER (potential comet XMAAS is now C/2015 F5 (SWAN-XINGMING)). It is visible high in the eastern morning skies from the SSO scopes, being around 39 degrees above the horizon at astronomical twilight, and remains high for most of April, disappearing in mid May to reappear in the evening sky.
Between the 19th and 22nd of April the comet is within T12 distance of the Helix nebula. On the 19th it is 1 degree away from the Helix Nebula, on the 20th it will be 33' from the nebula and on the the 21st it will be 43' away.
The ephemeris lists the comet as being magnitude 11 at this time. But currently it is around magnitude 9, about 2.5 magnitudes above the ephemeris predictions. It may possibly reach magnitude 6 in mid-May evening skies, passing through Eridanus and Lepus.
The Helix Nebula is magnitude 7.9, a stack of 10-15 1 -2 minute exposures may bring them both out nicely (Rolando Ligustri may advise differently).
MPC one line ephemeris:
CK15G020 2015 05 23.8022 0.779770 1.000000 257.4779 110.0566 147.5512 20150627 11.0 4.0 C/2015 G2 (MASTER)