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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').
Advanced Search

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"

32492 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  2. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  3. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  4. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  5. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  6. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  7. GRB 240421B: GRBAlpha detection
  8. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  9. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  10. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  11. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  12. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  13. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  14. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  15. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  16. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  17. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  18. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  19. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  20. GRB 240419A: Swift-BAT refined analysis
  21. GRB 240418A: Swift-BAT refined analysis
  22. LXT240402A/GRB240402B: Chandra X-ray detection
  23. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  24. GRB 240419A: Possible ATCA radio detection
  25. GRB 240421B: ATCA radio observations
  26. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  27. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  28. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  29. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  30. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  31. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  32. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  33. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  34. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  35. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  36. GRB 240421A: Glowbug gamma-ray detection
  37. GRB 240414A: radio detection with the VLA
  38. Fermi-LAT gamma-ray observations of IceCube-240419A
  39. GRB 240414A: AMI-LA radio observations
  40. GRB 240414A: LBT optical detection
  41. GRB 240419B : MITSuME Akeno optical upper limits
  42. Fermi GRB 240422A: Global MASTER-Net observations report
  43. GRB 240421B: AstroSat CZTI detection
  44. Fermi GRB 240421B: Global MASTER-Net observations report
  45. Swift GRB 240421B: Global MASTER-Net observations report
  46. GRB 240421B: Fermi GBM Observation
  47. GRB 240421B: J-band upper limits from WINTER
  48. GRB 240421B: Swift/UVOT Upper Limits
  49. Fermi GRB 240421A: Global MASTER-Net observations report
  50. EP240417a: no counterpart detection by SOAR
  51. EP240420a: TNT upper limit to its optical counterpart
  52. EP240420a: Nanshan optical counterpart observations
  53. EP240420a: GWAC-F50A optical upper limit
  54. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  55. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  56. EP240420a: NOT optical counterpart candidate and potential host
  57. GRB240419A: Skynet Optical Afterglow Analysis
  58. GRB240418A - Candidate afterglow from NIRES
  59. GRB 240419B: Swift/UVOT Upper Limits
  60. GRB 240419A: Swift/UVOT Upper Limits
  61. GRB 240419B: optical afterglow from the NOT
  62. EP240414a: Near-IR observations with NIRES and WINTER
  63. Swift GRB 240419B: Global MASTER-Net observations report
  64. EP240414A: Terskol Zeiss-2000 optical upper limit
  65. Swift GRB 240419A: Global MASTER-Net observations report
  66. GRB 240418A: Swift/UVOT Upper Limits
  67. GRB 240419A: REM NIR afterglow detection
  68. GRB 240411B: Swift/UVOT Detection
  69. EP240417a: YAHPT Optical Upper Limits
  70. GRB240418A: YAHPT Upper Limits
  71. GRB 240419A: VLT/UVES redshift of z = 5.178
  72. GRB 240419A: VLT optical afterglow detection
  73. EP240416a: J-band observations with WINTER
  74. EP240414a: GMG observation
  75. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  76. GRB 240418A: NOT optical upper limits
  77. GRB 240418A: AKO Upper Limit
  78. GRB 240411A: GOTO early optical upper limits
  79. Fermi GRB 240417A: Global MASTER-Net observations report
  80. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  81. EP240416A: Terskol Zeiss-2000 optical upper limit
  82. EP240416A: Khureltogoot optical upper limit
  83. Improved IPN triangulation of GRB 240411A
  84. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  85. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  86. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  87. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  88. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  89. GRB 240415A: Glowbug gamma-ray detection
  90. GRB 240414A: Glowbug gamma-ray detection
  91. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  92. GRB 240415B: GECAM-B detection
  93. EP 240416a: Xinglong and NOT decaying optical counterpart
  94. GRB 240415A: Swift-BAT refined analysis
  95. EP240416A: MASTER optical observations
  96. GRB 240411A: Glowbug gamma-ray detection
  97. GRB 240414A: Swift-BAT refined analysis
  98. EP240416a: Kinder optical counterpart candidate
  99. GRB 240414A: AbAO optical upprer limit
  100. GRB 240415A: Swift/UVOT Detection

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