HOP 0243

abstract of observational proposal

Objective: to observe effects in the chromosphere and transition region of weak, bipolar magnetic fields in quiet sun (intra-network fields or transient horizontal magnetic fields) using IRIS and Hinode

Scientific Background:

Weak, mixed-polarity signals have been observed with magnetographs in network cell interiors for decades. Accurate inference of their field strengths and inclinations became possible with the Hinode SP. Granular-sized transient horizontal magnetic fields (THMFs) are indeed ubiquitous in the photosphere (Lites et al. 2008, Orozco Suarez et al. 2007, Centeno et al. 2007, and Ishikawa et al. 2008). The amounts of magnetic flux and energy represented by these fields are very large, and they could contribute significantly to chromospheric and coronal heating. At least some of the THMFs reach above the photosphere (Martinez Gonzalez & Bellot Rubio 2009), and they may transport energy at a rate comparable to the radiative losses of the chromosphere (Ishikawa and Tsuneta 2009, Martinez Gonzalez et al. 2010). With Hinode's limited visibility of the chromosphere, it has not been possible to connect observations of the weak photospheric fields with any dynamical or heating events in the chromosphere or transition region. Coordinated observing with IRIS now provides that capability, with spatial resolution comparable to that of Hinode SP, and with both imaging and spectra covering the chromosphere and cooler transition region.

request to SOT

SOT should use a FOV slightly larger than that of IRIS in both dimensions, to allow for pointing inaccuracy, and cadence of 30-75 seconds, to follow the evolution of the weak fields. (For the BFI and NFI, the FOV should be at least 25 x 80 arcsec.)

(FG 0x04eb IHOP243 low-TLM, Shless Na IV 31x82", ROI 1, 32 s, Ca, CN)

[note: Check margin factor for SP]

SP: very fast maps, to obtain the required time resolution with enough slit positions to maximize the chance of overlap with the IRIS slit. Both sides of the CCD are used to increase SNR. Two programs have been tested so far:

SP 0x15b Very Fast Map, 9"x82", 2-side CCD, Q65, repeats: cadence = 73 sec, telemetry usage = 500 Mbits/hour

SP 0x190 HOP 243 low-TLM, Very Fast map 9x82, lower half

For a plage target observed with IRIS, use either

SP 0x0194 HOP 243 Plage, DynamicsMode 9x82, bottom half, uses ~1000 Mbits/hr
SP 0x0195 HOP 243 Plage, Lower-TLM DynMode, 9x82, bottom half, uses ~500 Mbits/hr

Note: margin factor
FG 0x4eb --- 1.3
SP 0x15b --- 0.6
SP 0x190 --- 0.6
SP 0x194 & 195 --- 0.5

(edited on 2016 Mar. 29)

request to EIS

EIS should run the following sequence:

PRY_slot_context_v3 (ID: 353, 3m 29s)
Cor_Hole_Jet_v1 (ID: 512; 6m 31s, 40"x168")
PRY_slot_context_v3

Cor_Hole_Jet_v1 should be repeated continuously to fill the available time-slot. The sequence should run continuously through SAA periods. The pointing for Cor_Hole_Jet_v1 should be centered on the IRIS field-of-view.

other participating instruments

Request to IRIS: IRIS should run a medium sit-and-stare, 2-step sparse, or 4-step dense raster, with exposure times of 8 or 15 sec, and slit jaw images in the 1400 and 2796 channels, with rotation tracking. Exact program(s) can be chosen in IRIS weekly meetings or during planning. After the time series, but while SOT is still running, a short program with slit jaw images in 1400, 2796, and 2832 should be run for a few repeats to help with coalignment.

The OBS to use is OBSID=3800258458, dur=112.0s, desc=Medium sparse 2-step raster 1x60 2s Si IV Mg II h/k Mg II w s Deep x 8 FUV spectrally rebinned x 2

(added on 2016/01/18)
Plage-version of the program:
When the target is plage, IRIS should run a 16-step dense raster with 0.5s exposure times and slit-jaw images in 2796, 1330, and 1400 channels, with rotation tracking. The OBS-ID to use is 3655502035.

remarks

The target should be quiet sun at or close to disk center; examples of both coronal hole and ordinary quiet sun are needed.

Minimum duration of each run should be 45 minutes, avoiding SAA; longer runs are desirable when telemetry allows.

The target coordinates could be chosen either by the Hinode or IRIS planners, depending on the phase of the Hinode planning cycle. If the SAA-free periods are not used, then coordination between the planners to avoid SAA in both spacecraft is necessary. IRIS SAA-free times are approximately 11-15 UT and 23 - 04 UT.