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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 231216A: 10.4 m GTC optical upper limit
  2. GRB 231215A: AMI-LA radio detection
  3. GRB 231216A: Nanshan/HMT optical upper limit
  4. GRB 231216A: LCOGT Optical Upper Limits
  5. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  6. GRB 231216A: Swift-XRT refined analysis correction
  7. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  8. GRB 231216A: Swift-XRT refined Analysis
  9. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  10. GRB 231216A: REM NIR upper limits
  11. GRB 231216A: Swift/UVOT Upper Limits
  12. GRB 231216A: Swift-BAT refined analysis
  13. GRB 231215A: Swift-BAT refined analysis
  14. GRB 231214A: Swift-BAT refined analysis
  15. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  16. GRB 231216A: GIT optical upper limit
  17. GRB 231216A: NOT optical upper limits
  18. GRB 231216A: BOOTES-2/TELMA optical upper limit
  19. GRB 231215A: GRBAlpha detection
  20. Swift GRB231216.77: Global MASTER-Net observations report
  21. GRB 231216A: Swift detection of a burst
  22. Konus-Wind detection of GRB 231215A
  23. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  24. GRB 231215A: NOT optical observations
  25. GRB 231214A: Swift/UVOT Upper Limits
  26. GRB 231215A: Redshift from OSIRIS+ / GTC
  27. GRB 231205B: VZLUSAT-2 detection
  28. GRB 231204A: VZLUSAT-2 detection
  29. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  30. GRB 231215A: Fermi GBM observation
  31. GRB 231215A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 231215A : OHP/T193 optical afterglow detection
  33. GRB 231215A: Swift/UVOT Detection
  34. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  35. GRB 231215A: Swift-XRT refined Analysis
  36. GRB 231215A: BOOTES-4/MET optical detection
  37. GRB 231215A: AKO Optical Upper Limit
  38. GRB 231215A: AGILE detection
  39. GRB 231214A: Fermi GBM observation
  40. Konus-Wind detection of GRB 231210B
  41. ATCA observations of GRB 231210B
  42. GRB 231215A: Enhanced Swift-XRT position
  43. Fermi trigger No 724326442: Global MASTER-Net observations report
  44. GRB 231214A: REM optical/NIR upper limits
  45. GRB 231215A: GROWTH-India optical follow-up
  46. GRB 231215A : Nanshan/HMT optical observations
  47. GRB 231215A: AstroSat CZTI detection
  48. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  49. GRB 231214A: Swift-XRT refined Analysis
  50. GRB 231215A: Mondy optical bright afterglow detection
  51. GRB 231214A: AstroSat CZTI detection
  52. GRB 231215C: MASTER OT detection
  53. Swift GRB231215.41: Global MASTER-Net observations report
  54. GRB 231215A: Swift-XRT observations
  55. GRB 231215B: Fermi GBM Final Real-time Localization
  56. GRB 231215A: Swift detection of a burst
  57. GRB 231214A: Fermi-LAT detection
  58. GRB 231214A: Enhanced Swift-XRT position
  59. GRB 231214B: Swift/BAT-GUANO detection of a burst
  60. GRB231214A: BOOTES-6/DPRT optical upper limit
  61. Fermi trigger No 724278269: Global MASTER-Net observations report
  62. Fermi trigger No 724233240: Global MASTER-Net observations report
  63. Swift GRB231214.85: Global MASTER-Net observations report
  64. GRB 231214A: Swift detection of a burst
  65. GRB 231214A: Fermi GBM Final Real-time Localization
  66. GRB 231210B: REM optical/NIR upper limits
  67. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  68. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  69. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  70. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 2047+098, located inside the IceCube-231211A error region
  71. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  72. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  73. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  74. GRB 231212A: GECAM-C detection of a likely short burst
  75. Fermi trigger No 724035412: Global MASTER-Net observations report
  76. GRB 231210B: MeerLICHT afterglow observations
  77. GRB 231210B: Swift-BAT refined analysis
  78. IceCube Alert 231211.03: Global MASTER-Net observations report
  79. IceCube-231202A: No candidates from the Zwicky Transient Facility
  80. GRB 231210B: Swift-XRT refined Analysis
  81. GRB 231210B: Enhanced Swift-XRT position
  82. GRB 231210B: VLT/X-shooter redshift
  83. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  84. Fermi trigger No 723906955: Global MASTER-Net observations report
  85. GRB 231210B: Swift detection of a burst with optical counterpart
  86. Swift GRB231210.90: Global MASTER-Net OT detection
  87. Swift GRB231210.90: Global MASTER-Net observations report
  88. IPN triangulation of GRB 231129C
  89. GRB 231210A: Fermi GBM Final Real-time Localization
  90. GRB 231208A: GRBAlpha detection
  91. GRB231205B: Swift/UVOT Upper Limits
  92. GRB 231208A: Glowbug gamma-ray detection
  93. GRB 231208A: AstroSat CZTI detection of a faint burst
  94. LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
  95. IPN triangulation of GRB 231205A
  96. GRB 231205B: Swift-BAT refined analysis
  97. GRB 231205B: 1.3m DFOT Optical upper limit
  98. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  99. GRB 231206A: joint location of multiple instruments by ETJASMIN
  100. GRB 231205B: optical upper limit in TSHAOand AbAO

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