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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"

28086 results found.

  1. GRB 230618A: Swift-XRT refined Analysis
  2. GRB 230616A: Swift-XRT observations
  3. LIGO/Virgo S230616aa: Global MASTER-Net observations report
  4. LIGO/Virgo S230615an: Global MASTER-Net observations report
  5. GRB230618A: LCOGT Optical Observations
  6. GRB 230618A: Swift detection of a burst
  7. LIGO/Virgo/KAGRA S230615az: T80S Search and Candidate Counterpart Identification
  8. GRB 230616A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  9. LIGO/Virgo/KAGRA S230615az: Xinglong-2.16m photometric observations of GIT candidates
  10. LIGO/Virgo/KAGRA S230529ay: Upper limits from a two-week IceCube neutrino search
  11. LIGO/Virgo/KAGRA S230615az: GROWTH-India candidates
  12. GRB 230614B: Fermi GBM Observation
  13. GRB 230614C: Fermi GBM Detection
  14. LIGO/Virgo S230613at: Global MASTER-Net observations report
  15. LIGO/Virgo S230614t: Global MASTER-Net observations report
  16. GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV
  17. Fermi trigger No 708426906: Global MASTER-Net observations report
  18. GRB 230606A: LCOGT Optical Observations
  19. IceCube-Cascade 230610A: Upper limits from a search for additional neutrino events in IceCube
  20. LIGO/Virgo/KAGRA S230608as: Updated Sky localization
  21. LIGO/Virgo/KAGRA S230606d: Updated Sky localization
  22. LIGO/Virgo/KAGRA S230609u: Updated Sky localization
  23. LIGO/Virgo/KAGRA S230609u: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo S230608as: Global MASTER-Net observations report
  25. ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
  26. LIGO/Virgo/KAGRA S230608as: Identification of a GW compact binary merger candidate
  27. Fermi GRB 230603A: Global MASTER-Net observations report
  28. Fermi trigger No 707039690: Global MASTER-Net observations report
  29. ZTF and GIT Observations of the Candidate Optical Afterglow AT2023jxk
  30. GRB 230606A: Swift-BAT refined analysis
  31. GRB 230606A: Gaoyazi/GOT optical upper limit
  32. GRB 230606A: Fermi GBM Observation
  33. GRB 230606A: Swift-XRT refined Analysis
  34. GRB 230604A: GRBAlpha detection
  35. GRB 230606A: Swift/UVOT Upper Limits
  36. GRB 230606A: Enhanced Swift-XRT position
  37. LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
  38. Fermi-LAT gamma-ray observations of IceCube-230603A
  39. LIGO/Virgo/KAGRA S230605o: Updated Sky localization
  40. IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
  41. LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
  42. LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo S230602ap: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
  45. GRB 230521A: VZLUSAT-2 detection
  46. GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
  47. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
  49. LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
  50. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  51. LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
  52. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  54. LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
  55. Alert from the HAWC Burst Monitor HAWC-230527A
  56. LIGO/Virgo S230525a: Global MASTER-Net observations report
  57. LIGO/Virgo/KAGRA S230518h: Updated Sky localization
  58. LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
  59. Fermi-LAT gamma-ray observations of IceCube-230524A
  60. LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
  61. GRB 230510A: Swift-BAT refined analysis
  62. GRB 230525A: Fermi GBM Detection
  63. LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
  64. IceCube-230524A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 230523B: GRBAlpha detection
  66. GRB 230524A: Fermi GBM Observation
  67. GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
  68. LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
  69. LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
  70. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
  71. LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
  72. GRB 230518B: VZLUSAT-2 detection
  73. IPN triangulation of GRB 230518A (short)
  74. Fermi trigger No 706317104: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  76. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  77. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  78. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
  79. GRB 230520A: MAXI/GSC detection
  80. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  81. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  82. GRB 230518A: Fermi GBM Observation
  83. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  84. LIGO/Virgo S230518h: AGILE/MCAL observations
  85. GRB 230518A: Swift/BAT-GUANO detection
  86. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  87. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  89. LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
  90. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  91. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  92. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  93. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  94. GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
  95. GRB 230510B: Fermi GBM detection
  96. IPN triangulation of GRB 230512A
  97. GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
  98. GRB 230512A: GIT non detection of afterglow candidate
  99. GRB 230512A: Kitab possible afterglow candidate
  100. Fermi trigger No 705565670: Global MASTER-Net observations report

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