HOP 0340

abstract of observational proposal

Main Objective: Create a nearly continuous XRT movie to coincide with approximately 90-minute-long ground-based white-light movie from the MegaMovie projectduring the 2017 Aug 21 total solar eclipse.

Scientific Justification: The total solar eclipse of 2017 Aug 21 will span the width of the entire continental United States. The Eclipse Megamovie Project (eclipsemega.movie) plans ground-base coronal observations along the eclipse path, resulting in a ~90-minute-long continuous white-light-eclipse corona movie, the first of its kind. We request XRT full-disk X-ray images at about 1-minute cadence to complement the white-light movie. The X-ray images, combined with the continuous ground-based white-light, SDO EUV images, and coronagraph images (with Sunward-edge limit well beyond what can be detected from the ground) will provide an unprecedented look at the continuous evolution of the corona over such a wide spectral range. Over the ~90-minute period, studies of coronal dynamics will be possible over a continuous hight span from the solar surface to the outer corona. X-ray coronal thermodynamic measurements will be possible via the inclusion of a second XRT filter, at reduced cadence.

request to XRT

We require approximately continuous full-disk coronal images for a 95-minute period coinciding with the ground-based totality over the US: 21 August 2017, 17:15 - 18:50 UT. Imaging is primarily to be in a “soft” band pass, such as Al-poly, with occasional images in a second filter, such as Al-mesh, to allow thermal analysis.

FIELD OF VIEW:1024x1024, with 2x2 binning.

FILTERS: Hi- and low-cadence pairs, with Al/poly for high cadence and Al/mesh for low cadence.

EXPOSURE TIME: Fixed-exposure image pairs, to form short-longexposure image composites. Suggestions are: for Al/poly, 4-5 sec + 0.5-1 sec; for Al/mesh, 2 sec + 0.25 sec.

CADENCE: About 60 seconds between image pairs. Al/poly would run for nine image pairs, followed by one Al/mesh pair, for a total time of about 10 min for each sequence. During times when the Sun is eclipsed from Hinode, images from only a single filter (the high-cadence filter) would be required.

remarks

Previous HOP information: HOPs 224, 280, 299; these were eclipse HOPs, but ground-based observations were hampered by clouds.

Additional Remarks: According to early predictions, during the period of the requested observations there will be no occultations of the Sun by the Moon as seen from Hinode. There is however a close approach at 18:25 UT, and if necessary, around this period (or at other periods as deemed appropriate by the COs), the HOP can continue with the high-cadence filter alone.

The HOP may also be interrupted for brief periods if there are other XRT eclipse-HOP requests conflicting with this request.