Observing with ASTE
Dear ASTE Users,
We have discovered a bug in the data reduction software Newstar/Nostar. In nutshell, the bug introduces a shift in the velocity of the output spectrum, and the shift becomes larger at larger frequency offset from the center of the band. The amount of velocity shift correlates with the systemic velocity of the source, and thus distant extragalactic sources are affected the most. Figures 1 illustrates this velocity calculation error (v_err) as functions of v_LSR and velocity offset with respect to vLSR (v_ch-v_LSR).
See this link for the solution to correct for this bug.
We appreciate your patience, and apologize for the inconvenience that this will cause. Please let us (aste-helpdesk@nao.ac.jp) know if you have any questions regarding this matter.
Sincerely,
Seiichi Sakamoto, Director, NAOJ Chile Observatory
Figure 1(top) the velocity error for MAC spectrometer using 512 MHz bandwidth, and (bottom) the same for WHSF spectrometer using 4GHz bandwidth.