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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"

32531 results found.

  1. Fermi GRB 230807A: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S230807f: Identification of a GW compact binary merger candidate
  3. Konus-Wind detection of GRB 230803A
  4. GRB 230805B: Fermi GBM observation
  5. GRB 230805B : OHP/T193 optical upper limit
  6. LIGO/Virgo/KAGRA S230806ak: Updated Sky localization and EM Bright Classification
  7. LIGO/Virgo/KAGRA S230806ak: Identification of a GW compact binary merger candidate
  8. GRB 230805B: Swift/UVOT Upper Limits
  9. GRB 230805B: Bassano Bresciano observatory upper limit
  10. GRB 230805B: NOT optical afterglow confirmation
  11. Fermi GRB 230805A: Global MASTER-Net observations report
  12. Swift GRB 230805B: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S230805x: Updated Sky localization
  14. LIGO/Virgo/KAGRA S230805x: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S230802aq: Updated Sky localization and EM Bright Classification
  16. GRB 230802B: AstroSat CZTI detection
  17. GRB 230802A: Fermi GBM observation
  18. GRB 230802A: Swift-BAT refined analysis
  19. IPN triangulation of GRB 230803A
  20. GRB 230802A: Swift/UVOT Upper Limits
  21. GRB 230803A: AstroSat CZTI detection
  22. Swift GRB 230802A: Global MASTER-Net observations report
  23. LIGO/Virgo/KAGRA S230802aq: Upper limits from Fermi-GBM Observations
  24. LIGO/Virgo S230802aq: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  25. LIGO/Virgo/KAGRA S230802aq: Coverage and upper limits from MAXI/GSC observations
  26. LIGO/Virgo/KAGRA S230802aq: Identification of a GW compact binary merger candidate
  27. IceCube-230724A: JCMT/SCUBA-2 submm observations
  28. IceCube-230707A: JCMT/SCUBA-2 submm observations
  29. GRB 230723A: SPT-3G millimeter-band transient event inconsistent with IPN position
  30. LIGO/Virgo/KAGRA S230731an: Updated Sky Localization and EM Bright Classification, and Correction to Source Classification
  31. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  32. LIGO/Virgo/KAGRA S230731an: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S230729z: Updated Sky localization
  34. GRB 230728A: Swift-BAT refined analysis
  35. Fermi-LAT gamma-ray observations of IceCube-230727A
  36. GRB 230723B: Swift-BAT refined analysis
  37. GRB 230723B: MITSuME Ishigaki optical observation
  38. IceCube-230727A: No candidates from the Zwicky Transient Facility
  39. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
  40. IceCube-230727A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 230728A: Fermi GBM Observation
  42. GRB 230728A: LCOGT Optical Upper Limit
  43. GRB 230728A: Swift/UVOT Upper Limits
  44. GRB 230728A: NOT optical observations and possible host galaxy
  45. IceCube-230724A: No counterparts from the Zwicky Transient Facility
  46. GRB 230727A: AstroSat CZTI detection
  47. GRB 230727A: Swift/BAT-GUANO detection of a burst
  48. Fermi-LAT gamma-ray observations of IceCube-230725A
  49. Fermi-LAT gamma-ray observations of IceCube-230724A
  50. IceCube-230725A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-230724A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 230723B: Further CAHA observations and host galaxy detection
  53. LIGO/Virgo/KAGRA S230726a: Updated Sky localization
  54. Konus-Wind detection of GRB 230723A
  55. GRB 230723B: MITSuME Akeno optical afterglow candidate detection
  56. GRB 230723B: ATCA rapid radio follow-up
  57. LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate
  58. GRB 230723B: GAD Observatory, La Spezia, Italy upper limit
  59. IPN triangulation of GRB 230723A (short)
  60. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  61. GRB 230723B: Montarrenti Observatory upper limit
  62. GRB 230723B: Optical afterglow candidate from CAHA
  63. GRB 230723B: Bassano Bresciano Observatory upper limit
  64. GRB 230723B: Fermi GBM observation
  65. GRB 230723B: non-detections from Observatoire de Haute-Provence
  66. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  67. GRB 230723B: Optical limit from CAHA
  68. GRB 230723B: Swift/UVOT Upper Limits
  69. Swift GRB 230723B: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  71. Fermi GRB 230723A: Global MASTER-Net observations report
  72. Swift Trigger 1180060 is not a GRB
  73. GRB 230718A: Final Localization Correction
  74. IPN triangulation of GRB 230712A (short)
  75. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  76. Fermi GRB 230713A: Global MASTER-Net observations report
  77. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  78. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  79. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  80. GRB 230709B: CALET Gamma-Ray Burst Monitor detection
  81. GRB 230703A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  83. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  84. GRB 230707A: Swift/BAT-GUANO position correction
  85. IceCube-230708A - Correction to GCN Circular 34170
  86. GRB 230709C: GRBAlpha detection
  87. GRB 230709B: GRBAlpha detection
  88. GRB 230709C: Fermi GBM Detection
  89. GRB 230707B: Fermi GBM Observation
  90. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  92. IceCube-230707A: No candidates detected by Swift-XRT
  93. Swift Trigger 1178410 is not an astrophysical event
  94. GRB 230709C: AstroSat CZTI detection
  95. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  96. GRB 230707B: CALET Gamma-Ray Burst Monitor detection
  97. GRB 230703A detected with multiple GRID detectors
  98. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  99. IceCube-230707A: No candidates from the Zwicky Transient Facility
  100. Fermi-LAT gamma-ray observations of IceCube-230708A

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