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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"

28054 results found.

  1. GRB 230802A: Enhanced Swift-XRT position
  2. LIGO/Virgo S230802aq: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  3. LIGO/Virgo/KAGRA S230802aq: Coverage and upper limits from MAXI/GSC observations
  4. LIGO/Virgo/KAGRA S230802aq: Identification of a GW compact binary merger candidate
  5. GRB 230802A: Swift detection of a burst
  6. IceCube-230724A: JCMT/SCUBA-2 submm observations
  7. IceCube-230707A: JCMT/SCUBA-2 submm observations
  8. LIGO/Virgo/KAGRA S230731an: Upper limits from Swift/BAT-GUANO
  9. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  10. LIGO/Virgo/KAGRA S230731an: Updated Sky Localization and EM Bright Classification, and Correction to Source Classification
  11. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  12. LIGO/Virgo/KAGRA S230731an: Identification of a GW compact binary merger candidate
  13. LIGO/Virgo/KAGRA S230729z: Updated Sky localization
  14. GRB 230723A: Detection of candidate millimeter-band radiation by SPT-3G
  15. Fermi trigger No 712390645: Global MASTER-Net observations report
  16. GRB 230728A: Swift-BAT refined analysis
  17. Fermi-LAT gamma-ray observations of IceCube-230727A
  18. GRB 230723B: Swift-BAT refined analysis
  19. Fermi trigger No 712306969: Global MASTER-Net observations report
  20. GRB 230723B: MITSuME Ishigaki optical observation
  21. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate
  22. IceCube-230727A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 230728A: BOOTES-1 optical upper limit
  24. GRB 230728A: Fermi GBM Observation
  25. GRB 230728A: LCOGT Optical Upper Limit
  26. GRB 230728A: Swift/UVOT Upper Limits
  27. GRB 230728A: Swift-XRT refined Analysis
  28. GRB 230728A: Enhanced Swift-XRT position
  29. GRB 230728A: NOT optical observations and possible host galaxy
  30. GRB 230728A: Swift detection of a burst
  31. GRB 230727A: Swift/BAT-GUANO detection of a burst
  32. Fermi-LAT gamma-ray observations of IceCube-230725A
  33. Fermi-LAT gamma-ray observations of IceCube-230724A
  34. IceCube-230725A: Upper limits from a search for additional neutrino events in IceCube
  35. IceCube-230724A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 230723B: Further CAHA observations and host galaxy detection
  37. LIGO/Virgo/KAGRA S230726a: Updated Sky localization
  38. GRB 230723B: MITSuME Akeno optical afterglow candidate detection
  39. LIGO/Virgo/KAGRA S230726b: one counterpart neutrino candidate from IceCube neutrino searches
  40. LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate
  41. GRB 230723B: GAD Observatory, La Spezia, Italy upper limit
  42. GRB 230723B: Leavitt Observatory upper limit
  43. GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
  44. GRB 230723B: Montarrenti Observatory upper limit
  45. GRB 230723B: Optical afterglow candidate from CAHA
  46. GRB 230723B: Bassano Bresciano Observatory upper limit
  47. GRB 230723B: Fermi GBM observation
  48. GRB 230723B: Swift-XRT refined Analysis
  49. GRB 230723B: non-detections from Observatoire de Haute-Provence
  50. LIGO/Virgo/KAGRA S230723ac: Updated Sky localization
  51. GRB 230723B: Optical limit from CAHA
  52. GRB 230723B: Swift/UVOT Upper Limits
  53. GRB 230723B: Swift-XRT observations
  54. LIGO/Virgo/KAGRA S230723ac: Identification of a GW compact binary merger candidate
  55. GRB 230723B: Swift detection of a burst
  56. IPN triangulation of GRB 230715D
  57. Swift Trigger 1180055 is not a GRB
  58. LIGO/Virgo/KAGRA S230708z: Updated Sky localization
  59. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  60. LIGO/Virgo/KAGRA S230709bi: Updated Sky localization
  61. LIGO/Virgo/KAGRA S230708t: Updated Sky localization
  62. GRB 230709C: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  63. IceCube-230708A: Upper limits from Swift/BAT-GUANO
  64. GRB 230709C: GRBAlpha detection
  65. GRB 230707B: Fermi GBM Observation
  66. LIGO/Virgo/KAGRA S230708z: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S230708t: Identification of a GW compact binary merger candidate
  68. IceCube-230707A: No candidates detected by Swift-XRT
  69. LIGO/Virgo/KAGRA S230708cf: Updated Sky localization
  70. GRB 230703A detected with multiple GRID detectors
  71. GRB 230709C: BALROG localization (Fermi Trigger 710617111 / GRB 230709735)
  72. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  73. Fermi-LAT gamma-ray observations of IceCube-230708A
  74. Fermi-LAT gamma-ray observations of IceCube-230707B
  75. Fermi-LAT gamma-ray observations of IceCube-230707A
  76. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  77. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  78. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  79. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  80. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  82. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  84. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  85. GRB 230707A: Swift-XRT observations
  86. GRB 230707A: Fermi GBM Detection
  87. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  88. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  89. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  90. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  91. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  92. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  93. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  94. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  96. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  97. Fermi trigger No 710117592: Global MASTER-Net observations report
  98. GRB 230626A: VZLUSAT-2 detection
  99. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  100. GRB 230328B: LBT detection of the likely host galaxy

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