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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"

23603 results found.

  1. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  2. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  3. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  4. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  5. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  6. Konus-Wind detection of GRB 250107C
  7. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  8. EP250108a: EP-FXT follow-up observation
  9. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  10. GRB 250109a: GMG Optical Upper Limit
  11. EP250109a: Swift/UVOT non-detection
  12. Konus-Wind detection of GRB 250107D (short/hard)
  13. IPN triangulation of GRB 250107C
  14. GRB 250108B: Swift-BAT refined analysis
  15. GRB 250108B: REM optical/NIR upper limits
  16. EP250109a: SVOM/VT optical candidate
  17. EP250109a: GOTO optical upper limits
  18. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  20. GRB 250108B: Swift-XRT refined Analysis
  21. GRB 250103A: 1.6m Mephisto optical observations
  22. GRB 250108A: Swift-XRT afterglow detection
  23. GRB 250108A:SVOM/VT optical candidate
  24. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  25. GRB 250103A: Swift-XRT afterglow detection
  26. GRB 250106A: SVOM/VT 2nd optical deep observation
  27. EPWXT01709129925: Xinglong optical observations
  28. GRB 250103B: REM optical/NIR upper limits
  29. GRB 250101A: REM optical/NIR counterpart detection
  30. GRB 250106A: Swift-XRT observations
  31. GRB 250106A: SVOM/VT optical candidate
  32. GRB 241229A: SVOM/VT optical upperlimit
  33. GRB 250103B: Swift-XRT refined Analysis
  34. GRB 250103A: Swift-XRT observations
  35. GRB 250103B：SVOM/VT optical counterpart
  36. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  37. GRB 250103A: Montarrenti Observatory optical detection
  38. GRB 250101A: further LCOGT optical afterglow observations
  39. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  40. GRB 250103A: SVOM/VT optical counterpart confirmation
  41. GRB 250103B: Swift detection of a burst
  42. GRB 250103A: GOTO optical upper limit
  43. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  44. GRB 250101A: Swift-BAT refined analysis
  45. GRB 250101A: further SAO RAS optical observations
  46. GRB 250101A: LCO optical counterpart detection
  47. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  48. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  49. GRB 250101A: Swift/UVOT Detection
  50. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  51. GRB 250101A: LCOGT optical afterglow detection
  52. GRB 250101A: OASDG optical observations
  53. GRB 250101A: SAO RAS observations of optical brightening
  54. GRB 250101A: BOOTES-4/MET optical afterglow detection
  55. GRB 250101A: SAO RAS optical observations
  56. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  57. GRB 250101A: GMG Optical Observation
  58. GRB 250101A: Swift detection of a burst with an optical counterpart
  59. EP241217a: VLA Radio Detection

  60. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  61. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  63. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  64. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  65. GRB 241229B: SAO RAS optical upper limit
  66. GRB 241228B: SAO RAS optical observations
  67. GRB 241229A: SAO RAS optical observations
  68. GRB 241229B: SVOM/VT optical candidate
  69. GRB 241229A: Swift-XRT observations
  70. Konus-Wind detection of GRB 241228A
  71. GRB 241229B: Swift-BAT refined analysis
  72. GRB241229B: UVOT upper limits
  73. GRB 241228B: D50 optical detection
  74. GRB 241228B: Swift-XRT afterglow detection
  75. GRB 241229B: Fermi GBM Observation
  76. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  77. GRB 241229A: GOTO optical upper limits
  78. GRB 241228B: LCO optical observation
  79. GRB 241228A: Swift-BAT refined analysis
  80. GRB 241229B: Swift detection of a burst
  81. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  82. GRB 241228B: GOTO24jmz optical follow-up observations
  83. GRB 241228B: TRT optical counterpart confirmation
  84. GRB 241228A: Swift-XRT refined Analysis
  85. GRB 241228A: Swift/UVOT Upper Limits
  86. GRB 241228B: GOTO possible optical counterpart candidate
  87. GRB 241228A: Swift detection of a burst
  88. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  89. GRB 241223A: GRBAlpha detection
  90. GRB 241212A: VZLUSAT-2 detection
  91. GRB 241029A: LCO optical observation
  92. GRB 241223A: Swift-XRT observations
  93. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  94. Fermi trigger No 756678579: Global MASTER-Net observations report
  95. EP241223a
  96. GRB 241223A: GOTO optical observations summary
  97. GRB 241105A: JWST photometric observations of the host galaxy
  98. EP241217a: e-MERLIN radio observations
  99. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  100. EP241021a: VLA radio detection

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