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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  2. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  3. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  4. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  5. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  6. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  7. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  8. GRB 240421B: GRBAlpha detection
  9. IceCube Alert 240424.08: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  11. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  12. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  13. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  14. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  15. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  16. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  17. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  18. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  19. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  20. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  21. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  22. GRB 240419A: Swift-BAT refined analysis
  23. GRB 240418A: Swift-BAT refined analysis
  24. LXT240402A/GRB240402B: Chandra X-ray detection
  25. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  27. GRB 240419A: Possible ATCA radio detection
  28. GRB 240421B: ATCA radio observations
  29. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  30. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  31. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  32. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  33. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  34. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  35. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  36. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  37. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  38. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  39. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  40. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  41. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  43. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  44. Fermi trigger No 735470374: Global MASTER-Net observations report
  45. GRB 240421A: Glowbug gamma-ray detection
  46. GRB 240414A: radio detection with the VLA
  47. Fermi-LAT gamma-ray observations of IceCube-240419A
  48. GRB 240414A: AMI-LA radio observations
  49. GRB 240414A: LBT optical detection
  50. GRB 240419B : MITSuME Akeno optical upper limits
  51. GRB 240415B: Swift-XRT observations
  52. GRB 240415A: Swift-XRT refined Analysis
  53. Fermi GRB 240422A: Global MASTER-Net observations report
  54. GRB 240421B: AstroSat CZTI detection
  55. GRB 240422A: Fermi GBM Final Real-time Localization
  56. GRB240421B: Zadko Observations
  57. Fermi GRB 240421B: Global MASTER-Net observations report
  58. Swift GRB 240421B: Global MASTER-Net observations report
  59. GRB 240421B: Fermi GBM Observation
  60. GRB 240421B: Swift-XRT refined Analysis
  61. GRB240421B: BOOTES-5/JGT optical upper limit
  62. GRB 240421B: J-band upper limits from WINTER
  63. GRB 240421B: Swift/UVOT Upper Limits
  64. GRB 240421B: Enhanced Swift-XRT position
  65. Fermi GRB 240421A: Global MASTER-Net observations report
  66. EP240417a: no counterpart detection by SOAR
  67. EP240420a: TNT upper limit to its optical counterpart
  68. EP240420a: Xinglong decaying optical counterpart
  69. GRB 240421B: Swift detection of a burst
  70. EP240420a: Nanshan optical counterpart observations
  71. EP240420a: GWAC-F50A optical upper limit
  72. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  73. GRB 240421A: Fermi GBM Final Real-time Localization
  74. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  75. EP240420a: NOT optical counterpart candidate and potential host
  76. Fermi trigger No 735280430: Global MASTER-Net observations report
  77. GRB240419A: Skynet Optical Afterglow Analysis
  78. GRB240418A - Candidate afterglow from NIRES
  79. IceCube Alert 240419.98: Global MASTER-Net observations report
  80. GRB 240419B: Swift/UVOT Upper Limits
  81. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  83. EP240420a: EP-WXT detection of a fast X-ray transient
  84. GRB 240419A: Swift/UVOT Upper Limits
  85. GRB 240419B: Swift-XRT refined Analysis
  86. GRB 240419B: optical afterglow from the NOT
  87. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  88. EP240414a: Near-IR observations with NIRES and WINTER
  89. Swift GRB 240419B: Global MASTER-Net observations report
  90. EP240414A: Terskol Zeiss-2000 optical upper limit
  91. GRB 240419B: Enhanced Swift-XRT position
  92. Swift GRB 240419A: Global MASTER-Net observations report
  93. GRB 240418A: Swift/UVOT Upper Limits
  94. GRB 240419A: REM NIR afterglow detection
  95. GRB 240419A: Swift-XRT refined Analysis
  96. GRB 240418A: Swift-XRT refined Analysis
  97. GRB 240419B: Swift detection of a burst
  98. GRB 240411B: Swift/UVOT Detection
  99. EP240417a: YAHPT Optical Upper Limits
  100. GRB240418A: YAHPT Upper Limits

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