HARDcam - Hydrogen-Alpha Rapid Dynamics camera

HARDcam is a very high cadence, high sensitivity solar imager which is installed as a common-user instrument on the Dunn Solar Telescope at the National Solar Observatory in New Mexico, USA. Initially commissioned on the telescope in July 2011, HARDcam has since provided data for high-impact publications appearing in a wealth of international peer-reviewed journals. HARDcam has the ability to be used alongside existing ROSA cameras as it can make use of the external synchronisation triggers synonymous with the ROSA instrument. Therefore, HARDcam can provide simultaneous high-resolution chromospheric observations to complement ROSA data sequences, with a typical frame rate over an order-of-magnitude higher than that provided by an existing ROSA camera. It employs an EMCCD which has been tuned to provide optimum sensitivity (95% QE) in the red portion of the electromagnetic spectrum, and typically observes under the following conditions:

  • Two-pixel spatial resolution = 158km @ H-alpha
  • Temporal resolution = 35 frames-per-second, but can achieve 200+ frames-per-second under ideal conditions

If you are interested in making use of HARDcam you should contact David Jess directly for information and advice.

Sample HARDcam images

The sample HARDcam snapshots shown below are designed to show the capabilities of the imaging system. Under normal circumstances the field-of-view is matched to that of ROSA to allow for easy coalignment between the instruments. Thus, by default the field-of-view is 70“ x 70”, but can be increased depending on the requirements of the observer. Please click on the images below to see full-size versions and/or play the respective movies.

Processing Pipeline

These movies are prepared to show the various stages of data reduction required to produce a final, science-ready data product. The first movie is a time series which has only been calibrated using dark subtraction and flat fielding. The second movie reveals the same time series, but now only speckle reconstructed. It is clear that while the spatial resolution has been drastically improved, small-scale turbulent fluctuations are still visible in the time series producing a “watery” effect. The final movie displays the fully-calibrated image sequence, consisting of dark subtracted, flat fielded, speckle reconstructed, and de-stretched consecutive images. This is a “science ready” data product according to the data reduction pipeline written by David Jess.

Movie A Movie B Movie C

Larger field-of-view of an Active Region

These images were acquired on the 07-Mar-2013, and consist of the G-band (upper left; 30.3 FPS), Na I D1 core (upper right; 15.15 FPS), Ca II K (lower left; 27 FPS), and the H-alpha core (lower right; 28 FPS). The G-band and Na I D1 images were acquired by ROSA, while the H-alpha and Ca II K images were obtained simultaneously by the HARDcam and DJCcam instruments, respectively. Here, the field-of-view has been increased to 120“ x 120” (instead of the default 70“ x 70”) in order to capture an entire active region as it crossed the solar disk.

Comparison with SDO/AIA field-of-view

These images were acquired on the 13-Jul-2011, and consist of an SDO/AIA 171 Angstrom image (upper left), with dashed white lines indicating the typical diffraction-limited ROSA field-of-view. The upper-right panel shows an interlaced SDO/AIA 4500 Angstrom and ROSA blue continuum image. The lower panels reveal the ROSA blue continuum (left) and HARDcam H-alpha core (right) images interlaced with a simultaneous SDO/AIA 171 Angstrom snapshot. Taken from Jess et al., ApJ, 757, 160 (2012)

Limb observations of a post-flare Active Region

This image was acquired on the 11-Feb-2012, and consists of a narrowband (0.025nm) H-alpha core snapshot of the Eastern limb in the aftermath of a flare. Even under mediocre seeing conditions, the high sensitivity of the HARDcam instrument allows for incredibly short exposure times to 'freeze' the atmospheric seeing and produce image sequences displaying fine scale structuring.

hardcam_limb.jpg

Useful documents

Publications

public/research_areas/solar_physics/hardcam.txt · Last modified: 2015/05/19 08:01 by David Jess

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