HOP 0412

plan term

2021/02/18-2021/02/18
2021/03/18-2021/03/18
2021/04/15-2021/04/15
2021/05/20-2021/05/20
2021/06/17-2021/06/17
2021/07/16-2021/07/16
2021/08/12-2021/08/12
2021/09/29-2021/09/29
2021/10/28-2021/10/28
2021/11/18-2021/11/18
2021/12/16-2021/12/16
2022/03/24-2022/03/24
2022/04/14-2022/04/14
2022/05/19-2022/05/19
2022/06/09-2022/06/09
2022/07/21-2022/07/21
2022/08/17-2022/08/17
2022/09/22-2022/09/22
2022/10/20-2022/10/20
2022/11/17-2022/11/17
2022/12/28-2022/12/28
2023/01/12-2023/01/12
2023/02/16-2023/02/16
2023/03/24-2023/03/24
2023/04/21-2023/04/21
2023/05/18-2023/05/18
2023/06/22-2023/06/22
2023/07/20-2023/07/20
2023/08/17-2023/08/17
2023/09/21-2023/09/21
2023/10/19-2023/10/19
2023/11/03-2023/11/03
2023/11/16-2023/11/16
2023/12/14-2023/12/14
2024/01/11-2024/01/11
2024/02/15-2024/02/15
2024/03/14-2024/03/14
2024/04/18-2024/04/18
2024/05/16-2024/05/16

abstract of observational proposal

Main Objective: To study how small-scale magnetic flux and solar irradiance varies over the sunspot cycle

Scientific Justification: The total solar irradiance varies by about 0.1% over the course of the solar cycle, primarily due to the influence of magnetic structures such as sunspots and faculae on the photospheric spectral irradiance. Short-term irradiance variation (on the scale of days-to-months) is well understood to be due to the balance of sunspots and facular areas as they cross the disk. However on the decadal scale of the solar cycle, questions remain as to why the irradiance variation can lead and/or lag the active region count over the course of the cycle. Explanations ranging from changes inthe solar diameter in response to magnetic flux storage in the convection zone to changes in the surface area of the photosphere due to F-mode modulation have been put forward.

We propose to observe a north-to-south latitudinal strip with SOT-SP on a regular basis to better understand the variation of irradiance with rising flux levels in the photosphere. These observations have the potential to reveal new and important aspects of the relation between solar irradiance and magnetic flux emergence over the solar cycle when compared with TSI measurement satellites such as TSIS-1 and TSIS-2.

In addition, work by Shiozu and Tsuneta has shown that HOP 79 N-S scan scan data can be used to infer the latitudinal temperature variation between the equator and the poles thus offering constraints on "thermal wind" theories of convection zone rotational profiles. Lites, Centeno, and McIntosh 2014 analyzed the north-to-south latitudinal strip with SOT/SP (HOP79) for the period Nov 2008 to May 2013, the rising phase of Cycle 24. They found that the smallest scale flux did not appear to vary along with the large-scale flux of the cycle, while a polarity transition at the polar region was observed. Further synoptic observations can be used to compare changes in small-scale flux along the meridian for a second solar minimum period, as well as for Cycle 25 which could potentially be stronger than Cycle 24.

request to SOT

This HOP uses the same program and pointing scheme as the north-south component of HOP79:

・ Perform a series of 20 scans spanning the central meridian on a monthly basis, avoiding SSA intervals
・ 30” normal maps at each pointing using SOT-SP program 0x008a
・ Duration: about 12 hours (longer during eclipse season)

The list of pointings for this HOP can be determined using the following SSWIDL commands, once the orbital events file is available:

get_pnt_times_hop412,'21-feb-2023', lon=0, ts_win='21-feb-2023 13:00', /bfi, dt_dwell_min=23, /no_plot
(note: pointing interval 23 min)

Then, you will get the list of pointings in a specific format as follows:

POINTING:
2023/02/21 13:06:00.000 | -21 | -984 | HOP412 01/20
2023/02/21 13:29:00.000 | -21 | -884 | HOP412 02/20
2023/02/21 13:52:00.000 | -21 | -784 | HOP412 03/20
2023/02/21 14:15:00.000 | -21 | -684 | HOP412 04/20
2023/02/21 14:38:00.000 | -21 | -584 | HOP412 05/20
2023/02/21 15:01:00.000 | -21 | -484 | HOP412 06/20
2023/02/21 15:24:00.000 | -21 | -384 | HOP412 07/20
2023/02/21 16:08:30.000 | -21 | -284 | HOP412 08/20
2023/02/21 16:31:30.000 | -21 | -184 | HOP412 09/20
2023/02/21 16:54:30.000 | -21 | -84 | HOP412 10/20
2023/02/21 17:55:00.000 | -21 | 6 | HOP412 11/20
2023/02/21 18:18:00.000 | -21 | 106 | HOP412 12/20
2023/02/21 18:41:00.000 | -21 | 206 | HOP412 13/20
2023/02/21 19:32:00.000 | -21 | 306 | HOP412 14/20
2023/02/21 19:55:00.000 | -21 | 406 | HOP412 15/20
2023/02/21 20:18:00.000 | -21 | 506 | HOP412 16/20
2023/02/21 21:08:30.000 | -21 | 606 | HOP412 17/20
2023/02/21 21:31:30.000 | -21 | 706 | HOP412 18/20
2023/02/21 21:54:30.000 | -21 | 806 | HOP412 19/20
2023/02/21 22:45:30.000 | -21 | 906 | HOP412 20/20
2023/02/21 23:08:30.000 | 0 | 0 | End of HOP412
EOP

Send the list to CP through the chat system of Zoom in daily meetings (early and latter in twice; up to 1024 characters in one shot). CP will include it into the Daily Event Page, and the Pointing Tool will grab the pointing information in the timeline semi-automatically.

request to EIS

HOP79 was originally intended for long term variation of solar irradiance measurement and provides an ideal framework for studying center-to-limb variation of Doppler shift. Net Doppler shifts reported in previous papers indicate that transition region emissions (105K) are red-shifted up to +10 km s-1 while coronal emissions (106 K) are slightly blueshifted or almost at rest. EIS will allow precise measurement of coronal emissions. This modification will increase the value of the HOP while keeping its current scheme.

As with HOP79, the request for EIS includes spectra as well as slot images. Two studies should be run at each pointing:

・ Study #375 SK DEEP 5x512 SLIT1, Slit scan covering 5”x512”, data volume, 7Mbits in 11min

・ Study #354 PRY slot contextLITE, a composite image of 488”x488” in He II, data volume: 2.4Mbits in 4min

If two studies can not be accommodated at each pointing due to telemetry shortage or time allocation, they can be alternated from one pointing to the next.