search_lightcurve(cadence="short") includes FFI-based data for TESS sector 56+ / Cycle 5+

[orionlee]

Problem description

For search_lightcurve(cadence="short") would include various TESS FFI-based HLSP for sectors 56+, when FFI's exposure time is reduced to 200 seconds starting from cycle 5.

Example

import lightkurve as lk
# insert code here ...

# pi Men
sr = lk.search_lightcurve("TIC261136679", mission="TESS", cadence="short")
print(sr)

SearchResult includes those based on 200 seconds FFIs:

 #     mission     year   author  exptime target_name distance                proposal_id               
                                     s                 arcsec                                           
--- -------------- ---- --------- ------- ----------- -------- -----------------------------------------
  0 TESS Sector 04 2018      SPOC     120   261136679      0.0           G011183_G011132_G011048_G011250
  1 TESS Sector 01 2018      SPOC     120   261136679      0.0           G011183_G011132_G011048_G011250
...            ...  ...       ...     ...         ...      ...                                       ...
 18 TESS Sector 67 2023      SPOC     120   261136679      0.0                             G05144_G05155
 19 TESS Sector 62 2023 TESS-SPOC     200   261136679      0.0                                       N/A
 20 TESS Sector 61 2023 TESS-SPOC     200   261136679      0.0                                       N/A
 21 TESS Sector 66 2023       QLP     200   261136679      0.0                                       N/A
 22 TESS Sector 65 2023       QLP     200   261136679      0.0                                       N/A
...

Expected behavior

Environment

• lightkurve version (e.g. 1.0b6): 2.4.2

[orionlee]

One expedient way to fix it is to change the short cadence threshold from 300 seconds to 200 seconds. Would there be any unintended side effects?

lightkurve/src/lightkurve/search.py

Lines 1377 to 1382 in 5e4c619

	elif exptime in ["short"]:
	mask &= (products["exptime"] >= 60) & (products["exptime"] < 300)
	elif exptime in ["long", "ffi"]:
	mask &= products["exptime"] >= 300
	return mask

[Nschanche]

Hi @orionlee , good point. I tend to think people who use the 'short cadence' flag do actually want the postage stamp products, not FFI data. I will think on how we want to handle this. Thanks for the suggestion!

[orionlee]

BTW, the issue is also applicable to search_targetpixelfile(), because TESS-SPOC HLSP also releases TPFs, in addition to lightcurve files. For example,

> print(lk.search_targetpixelfile("TIC261136679", mission="TESS", sector=61, cadence="short"))

#     mission     year   author  exptime target_name distance  proposal_id 
                                     s                 arcsec               
--- -------------- ---- --------- ------- ----------- -------- -------------
  0 TESS Sector 61 2023      SPOC     120   261136679      0.0 G05144_G05155
  1 TESS Sector 61 2023 TESS-SPOC     200   261136679      0.0           N/A

[Nschanche]

I've put in PR #1410 that implements this fix (ie, short cadence is now <200 rather than < 300 so that FFI data is not returned.