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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"

28057 results found.

  1. GRB 230606A: Swift-BAT refined analysis
  2. GRB 230606A: Gaoyazi/GOT optical upper limit
  3. GRB 230606A: Fermi GBM Observation
  4. GRB 230606A: Swift-XRT refined Analysis
  5. GRB 230604A: GRBAlpha detection
  6. GRB 230606A: Swift/UVOT Upper Limits
  7. GRB 230606A: Enhanced Swift-XRT position
  8. LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
  9. Fermi-LAT gamma-ray observations of IceCube-230603A
  10. LIGO/Virgo/KAGRA S230605o: Updated Sky localization
  11. IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
  12. LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
  13. LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo S230602ap: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
  16. GRB 230521A: VZLUSAT-2 detection
  17. GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
  18. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
  20. LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
  21. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  22. LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
  23. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  24. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  25. LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
  26. Alert from the HAWC Burst Monitor HAWC-230527A
  27. LIGO/Virgo S230525a: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S230518h: Updated Sky localization
  29. LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
  30. Fermi-LAT gamma-ray observations of IceCube-230524A
  31. LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
  32. GRB 230510A: Swift-BAT refined analysis
  33. GRB 230525A: Fermi GBM Detection
  34. LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
  35. IceCube-230524A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 230523B: GRBAlpha detection
  37. GRB 230524A: Fermi GBM Observation
  38. GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
  39. LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
  40. LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
  41. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
  42. LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
  43. GRB 230518B: VZLUSAT-2 detection
  44. IPN triangulation of GRB 230518A (short)
  45. Fermi trigger No 706317104: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  47. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  48. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  49. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
  50. GRB 230520A: MAXI/GSC detection
  51. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  52. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  53. GRB 230518A: Fermi GBM Observation
  54. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  55. LIGO/Virgo S230518h: AGILE/MCAL observations
  56. GRB 230518A: Swift/BAT-GUANO detection
  57. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  58. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  59. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  60. LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
  61. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  62. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  63. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  64. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  65. GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
  66. GRB 230510B: Fermi GBM detection
  67. IPN triangulation of GRB 230512A
  68. GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
  69. GRB 230512A: GIT non detection of afterglow candidate
  70. GRB 230512A: Kitab possible afterglow candidate
  71. Fermi trigger No 705565670: Global MASTER-Net observations report
  72. Fermi-LAT gamma-ray observations of IceCube-230511A
  73. GRB 230510A: OHP/T193 and OHP/T120 optical observations
  74. GRB 230512A: Swift-XRT observations
  75. IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
  76. IceCube-Cascade 230511A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 230512A: GIT optical follow-up ZTF candidates
  78. GRB 230512A: Fermi GBM detection
  79. GRB 230512A: Fermi-LAT detection
  80. GRB 230512A: Fermi GBM Final Localization
  81. GRB 230510A: GIT optical upper limits
  82. GRB 230510A: LCOGT Optical Upper Limit
  83. GRB 230510A: Swift/UVOT Observations
  84. GRB 230510B: AstroSat CZTI detection
  85. GRB 230510A: Fermi GBM detection
  86. Fermi trigger No 705446499: Global MASTER-Net observations report
  87. GRB 230510A: Gaoyazi/GOT optical upper limit
  88. GRB 230510A: Nanshan/NEXT optical afterglow detection
  89. GRB 230510B: MAXI/GSC detection
  90. GRB 230506B: Fermi GBM detection
  91. GRB 230510A: Swift-XRT refined Analysis
  92. GRB 230510A: Enhanced Swift-XRT position
  93. GRB 230506C: Fermi GBM detection
  94. GRB 230510A: Swift detection of a burst
  95. GRB 230506C: SAO RAS optical observations
  96. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  97. Fermi-LAT gamma-ray observations of IceCube-230506A
  98. GRB 230506C: Swift-XRT refined Analysis
  99. GRB 230506C: Swift-BAT refined analysis
  100. GRB 230506B: Swift-BAT refined analysis

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Download all Circulars as a .tar.gz archive (updated once a day):
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