Hectospec & Hectochelle
Hectospec (Available-except for December 20 through January 20 due to cold temperatures; ambient air temp must be above 20°F): a moderate resolution spectrograph at R = 1000 to 2500 and exploits all 300 available fibers. Hectospec’s wavelength range covers 3650 – 9200Å. The instrument contact is Dan Fabricant. (Hectospec is not considered a PI instrument for SAO and UAO observers.)
Hectochelle (Available-except for December 20 through January 20 due to cold temperatures; ambient air temp must be above 20°F): an echelle spectrograph operating at and R range of 32,000 – 40,000, and a wavelength range of 3800 – 9000Å. Due to optical properties the image from on 240 of the fibers fall on the Hectochelle detectors. It is a single order instrument and there are 11 order-separting filters available. The instrument contact is Andrew Szentgyorgyi. (Hectochelle is not considered a PI instrument for SAO and UAO observers.)
Note: Hectospec and Hectochelle observing are run in queue mode. Astronomers do not need to be present at the MMT for their observations.
| Instrument | Grating (lpmm) | Spectral Range (Å) | Blaze Wavelength (Å) | Dispersion (Å/pix) | RMS image diameter (pix) |
| Hectospec | 270 | 3650 – 9200 | 5200 | 1.21 | 5 |
| Hectospec | 600 | 5300 – 7800 | 6000 | 0.55 | 5 |
| Hectochelle | 110 | 3800 – 9000 | / | 0.04 | 5 |
Hectospec and Hectochelle are two large bench mounted spectrographs that are fiber fed by 300, 25m long optical fibers from the telescope’s Cassegrain focus. A common to both spectrographs robotic positioner that is mounted behind the f/5 beam uses a pair of six-axis robots, dubbed Fred and Ginger, to reconfigure all 300 fibers over the 1deg focal surface to an accuracy of ~25um in just 300 seconds. Each fiber that is held magnetically on the focal surface has a core diameter of 250um that subtends to 1.5″ on the sky. Adjacent fibers can be spaced as closely as 20″ and is positioned using a complex algorithm.
Hectospec is a moderate-resolution, multiobject optical spectrograph, it offers 5770Å of spectral coverage at ~6Å resolution in the 350 to 1000 nm band. A higher dispersion grating offering ~3Å resolution is also available.
The Hectochelle adds a high dispersion capability to Hectospec’s moderate dispersion with a second, very large bench-mounted spectrograph using an echelle grating. Hectochelle uses 240 of the possible 300 fibers and attains R~32,000 (sigma~4 km/s) over a single, filter-selected orders.
For greater details about the instruments, how to prepare for your observations, your responsibilities, tips on data collection and reduction and links to all supporting documentation please see the Hectospec webpages and the Hectochelle webpages. IDL Software for the reduction of Hectospec data can be found here (please contact Ben Weiner with any questions).