It didn’t show up using the 2019 long-term ephem, but looking at it in STK it does seem like with just a little tweak in timing you could get the slightest overlap between (from the spacecraft’s perspective) the left edge of the sun and the right edge of the moon (or maybe it was the other way around).

Given the short duration despite the high altitude, I assume the is a very slight penumbral eclipse, like 95% of the sun still visible. I really doubt the spacecraft will notice it at all.

From: Ken Fairchild <kwfairchild@gmail.com>
Sent: Tuesday, February 20, 2024 1:40 PM
To: NIgel Angold <nangold@princeton.edu>
Cc: Wesley, Sheral R [US] (SP) <Sheral.Wesley@ngc.com>; Perry, Timothy E [US] (SP) <Timothy.Perry@ngc.com>; carol.weaver@unh.edu; Chubin, Eric [US] (SP) <Eric.Chubin@ngc.com>; David.Heirtzler@unh.edu; ADS-IBEX@l3harris.com; IBEXOPS@gmail.com; isocops@lists.sr.unh.edu; Ken.Fairchild@unh.edu; Paul.Janzen@mso.umt.edu; Tyler, Ryan S [US] (SP) <Ryan.Tyler@ngc.com>; Wynn, Reese [US] (SP) <Reese.Wynn@ngc.com>
Subject: EXT :Re: IBEX Orbit #640 ATS Approval (3 Mar - 12 Mar 2024)

Nigel,

Yeah, I was surprised when I saw it in the new forecast OEF.  I asked FDG about it and it was predicted.  It appeared in last year's MC analysis.  It is unusual that we didn't see it until this month though.  It is pretty short and that may be the reason why.  I didn't ping Ryan about it.

Ken

On Tue, Feb 20, 2024 at 1:13 PM NIgel Angold <nangold@princeton.edu> wrote:

Hmm, I wasn't expecting a penumbral eclipse until 29 April 2024. It's very short but does FDG see this too?

Nigel

Wesley, Sheral R [US] (SP)

February 20, 2024 at 09:56

All,

   Attached are the planning files for Orbit #639. Please respond to this thread with comments and approvals. Approvals are required by COB 21 Feb 2024.

Please note the following:

1. No Battery Balancing

2. SHORT Eclipse ASC. Apogee/ No eclipse commands needed

3. Command Load Constraint Violation Report (CCVR)

IBEX_2024_063_o0640a_v001.ccvr

# Input files:         1

#   IBEX_2024_063_o0640a_v001.scr

==========================

HARD CONSTRAINT VIOLATIONS

==========================

NO VIOLATIONS.

==========================

SOFT CONSTRAINT VIOLATIONS

==========================

IBX-CLC-016: No command to enable spin pulse protection was found after

             transition to science mode at 2024/03/03 11:05:15 UTC

IBX-CLC-016: No command to enable spin pulse protection was found after

             transition to science mode at 2024/03/07 06:05:18 UTC

==============

OTHER MESSAGES

SHORT Eclipse ASC. Apogee/ No eclipse commands needed

2024-03-07T01:32:28.336Z,PenumbraEntry,orbit:640

2024-03-07T01:32:28.336Z,EclipseEntry,moderate:false,long:false,orbit:640

2024-03-07T01:45:14.277Z,PenumbraExit,orbit:640

2024-03-07T01:45:14.277Z,EclipseExit,moderate:false,long:false,orbit:640

==============

NO MESSAGES.

Best Regards,

Sheral Wesley  | Sr Principal Engineer, Satellite Systems

Northrop Grumman Corporation  |  Space Systems

O: 703-406-5641  |  C: 202-236-0802  |  sheral.wesley@ngc.com

Perry, Timothy E [US] (SP)

February 8, 2024 at 10:25

All, 

   Attached are the planning files for Orbit #639. Please respond to this thread with comments and approvals. Approvals are required by COB 12 February 2024.

Please note the following: 

1.        No Battery Balancing

Eclipse Flag True: 2024/03/03 01:00:00

Eclipse Flag False: 2024/03/03 02:30:00

2. Command Load Constraint Violation Report (CCVR) 

IBEX_2024_053_o0639a_v001.ccvr

# Input files:         1

#   IBEX_2024_053_o0639a_v001.scr

==========================

HARD CONSTRAINT VIOLATIONS

==========================

NO VIOLATIONS.

==========================

SOFT CONSTRAINT VIOLATIONS

==========================

IBX-CLC-016: No command to enable spin pulse protection was found after

             transition to science mode at 2024/02/23 06:39:01 UTC

IBX-CLC-016: No command to enable spin pulse protection was found after

             transition to science mode at 2024/02/27 13:17:14 UTC

==============

OTHER MESSAGES

==============

NO MESSAGES.

Timothy E.Perry

CRS IBEX OCO-2

Mission Operations

timothy.perry@ngc.com

Office (703) 406-5976

IBEX MOC (703)404-7470

Cell (301) 606-1430

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