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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

16161 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  2. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  3. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  4. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  5. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  6. EP240426a: YAHPT optical upper limit
  7. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  8. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  9. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  10. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  11. EP240426a: GMG optical upper limit
  12. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  13. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  14. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  15. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  16. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  17. LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts
  18. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  19. LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
  20. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  21. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  22. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  23. LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm
  24. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  25. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  26. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  27. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  28. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  29. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  30. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  31. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  32. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  33. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  34. LXT240402A/GRB240402B: Chandra X-ray detection
  35. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  36. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  37. GRB 240414A: LBT optical detection
  38. GRB 240419B : MITSuME Akeno optical upper limits
  39. GRB240421B: BOOTES-5/JGT optical upper limit
  40. GRB 240421B: Swift/UVOT Upper Limits
  41. EP240417a: no counterpart detection by SOAR
  42. EP240420a: TNT upper limit to its optical counterpart
  43. EP240420a: Xinglong decaying optical counterpart
  44. EP240420a: Nanshan optical counterpart observations
  45. EP240420a: GWAC-F50A optical upper limit
  46. EP240420a: NOT optical counterpart candidate and potential host
  47. GRB240419A: Skynet Optical Afterglow Analysis
  48. GRB240418A - Candidate afterglow from NIRES
  49. GRB 240419B: Swift/UVOT Upper Limits
  50. GRB 240419A: Swift/UVOT Upper Limits
  51. GRB 240419B: optical afterglow from the NOT
  52. EP240414a: Near-IR observations with NIRES and WINTER
  53. EP240414A: Terskol Zeiss-2000 optical upper limit
  54. GRB 240418A: Swift/UVOT Upper Limits
  55. GRB 240419A: REM NIR afterglow detection
  56. GRB 240411B: Swift/UVOT Detection
  57. EP240417a: YAHPT Optical Upper Limits
  58. GRB 240419A: VLT/UVES redshift of z = 5.178
  59. GRB 240419A: VLT optical afterglow detection
  60. EP240416a: J-band observations with WINTER
  61. EP240414a: GMG observation
  62. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  63. GRB 240418A: NOT optical upper limits
  64. GRB 240411A: GOTO early optical upper limits
  65. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  66. EP240416A: Terskol Zeiss-2000 optical upper limit
  67. EP240416A: Khureltogoot optical upper limit
  68. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  69. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  70. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  71. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  72. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  73. EP 240416a: Xinglong and NOT decaying optical counterpart
  74. EP240416A: MASTER optical observations
  75. EP240416a: Kinder optical counterpart candidate
  76. GRB 240414A: AbAO optical upprer limit
  77. GRB 240415A: Swift/UVOT Detection
  78. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  79. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  80. GRB 240415A: Earliest optical followup with the Kinder observations
  81. EP 240414a: BOOTES-4/MET Optical Upper Limits
  82. EP240414a: EP-FXT follow-up observation
  83. GRB 240415A: OHP/T193 optical observations
  84. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  85. GRB 240415A: SAO RAS optical observations
  86. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  87. GRB 240415A: Mondy optical transient detection
  88. GRB 240414A: Photometric observation from 2.2m CAHA
  89. GRB 240414A: Swift/UVOT Detection
  90. LXT 240402A/GRB 240402B: Swift follow-up observations
  91. GRB 240414A: Mondy optical observations
  92. GRB 240414A: AKO Optical Upper Limit
  93. EP 240414a: NOT optical counterpart confirmation
  94. GRB240414A : J-band upper limits from WINTER
  95. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  96. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  97. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  98. EP240413A: GOTO optical upper limits
  99. GRB 240414A: Skynet Optical Afterglow Observations
  100. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3

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