6.1. Example 3 - Datasets description

In this example, we will reduce Flamingos 2 R3K longslit observations centered in the K-band of the superluminal microquasar GRS 1915+105.

The 2-pixel slit is used and the central wavelength is set to 2.2 {\mu}m. For expediency, we will reduced only the last eight frames of the long sequence. The dither pattern is AABB-AABB.

The calibrations we use for this example are:

  • Darks with exposure times matching the flats, the arcs, the telluric star observation, and the science observations. The darks are taken once a week. See Why darks are used for addtional information.

  • Lamp-on flats taken in the same configuration as the science and the telluric star and obtained at night after the science and telluric sequences.

  • Arcs taken taken in the same configuration as the science and the telluric star and obtained at night after the science and telluric sequences.

  • A telluric standard observation taken in the same configuration as the science and obtained, in this case, just after the completion of the science sequence, and at a similar airmass.

Here is the breakdown of the files. All the files are included in the tutorial data package. They can also be downloaded from the Gemini Observatory Archive (GOA). The science program is GS-2023A-DD-109.

Science
S20230606S0083-090

Science darks (120s)
S20230610S0434-440

Science flat
S20230606S0091

Science flat darks (16s)
S20230610S0217,220,223,225,227,230,232,235

Science arc
S20230606S0093

Science arc darks (180s) |

S20230610S0343-349

Science arc flat
Same as science flat

Telluric
S20230606S0097-100

Telluric darks (15s)
S20230610S0200,203,205,208,211,213

Telluric flat
S20230606S0101

Telluric flat darks (16s)
Same as science flat darks

Telluric arc
S20230606S0103

Telluric arc darks
Same as science arc darks

Telluric arc flat
Same as telluric flat

Note

In the R3K K-band configuration, a lamp-off flat matching the arc’s exposure time is obtained with the sequence. There is thermal emission in the arc lamp data. The lamp-off is used to removed that background, which is a required step when using the Gemini IRAF package.

This lamp-off and the removal of the thermal background is NOT required in DRAGONS. The wavelength solution algorithm in DRAGONS takes care of the background. In DRAGONS, the recommended reduction procedure is to ignore the lamp-off flat. However, if you still wish to use it, see Using the Lamp-off Flat for the K-band Arc for how to do it.