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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"

24636 results found.

  1. GRB 250106A: SVOM/VT optical candidate
  2. The EP-WXT trigger 01709129925 is likely a flaring star
  3. GRB 250103B: Swift-XRT refined Analysis
  4. GRB 250103B: LCO/1m optical afterglow candidate detection
  5. GRB 250103A: Bassano Bresciano Observatory upper limit
  6. GRB 250103A: Swift-XRT observations
  7. GRB 250101A: 1.3m DFOT optical afterglow detection
  8. GRB 241229A: 1.3m DFOT upper limit
  9. GRB 241228B: 1.3m DFOT Optical observations
  10. GRB 241228A: 1.3m DFOT upper limit
  11. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  12. GRB 250103A: Montarrenti Observatory optical detection
  13. GRB 250101A: further LCOGT optical afterglow observations
  14. GRB 250103A: TSHAO optical upper limit
  15. GRB 250103A: Fermi GBM Observation
  16. GRB 250103B: LCOGT Optical Upper Limit
  17. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  18. EP250101a: Liverpool Telescope optical upper limit
  19. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 250101a: Liverpool Telescope optical follow-up
  21. GRB 250103B: Swift detection of a burst
  22. GRB 250103A: Xinglong 2.16m Optical Candidate
  23. GRB 250101B: SVOM/GRM observation
  24. GRB 250103A: GOTO optical upper limit
  25. GRB 250103A: SVOM/C-GFT optical upper limit
  26. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  27. EP241231b: optical upper limit with the Liverpool Telescope
  28. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  29. GRB 250103A: SVOM detection of a long burst
  30. EP250101a: Xinglong optical upper limit
  31. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  32. GRB 250101A: Swift-BAT refined analysis
  33. GRB 250101A: further SAO RAS optical observations
  34. GRB 250101A: LCO optical counterpart detection
  35. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  36. GRB 250101A: Swift/UVOT Detection
  37. GRB 250101A: 1.6m Mephisto multi-band optical followup
  38. GRB 250101A: Swift-XRT refined Analysis
  39. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  40. GRB 250101A: LCOGT optical afterglow detection
  41. GRB 250101A: OASDG optical observations
  42. GRB 250101B: Fermi GBM Final Real-time Localization
  43. GRB 250101A: SAO RAS observations of optical brightening
  44. GRB 250101A: BOOTES-4/MET optical afterglow detection
  45. GRB 250101A: AKO Optical Afterglow Detection
  46. GRB 250101A: SAO RAS optical observations
  47. GRB 250101A: Enhanced Swift-XRT position
  48. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  49. GRB 250101A: SVOM/C-GFT early optical observations
  50. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  51. GRB 250101A: Nanshan/HMT optical observations
  52. GRB 250101A : GIT optical detection
  53. GRB 250101A: GMG Optical Observation
  54. GRB 250101A: Swift detection of a burst with an optical counterpart
  55. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  56. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  57. GRB 241229B: Continued CrAO ZTSh observations
  58. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  59. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  60. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  61. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  62. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  63. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  64. GRB 241229B: SVOM/GRM observation
  65. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  66. EP241217A: J band upper limit by SYSU 80cm telescope
  67. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  68. GRB 241229B: SAO RAS optical upper limit
  69. GRB 241228B: SAO RAS optical observations
  70. GRB 241229A: SAO RAS optical observations
  71. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 241229A: Swift-XRT observations
  73. EP240702a: 7DT Optical upper limits
  74. GRB 240606B: 7DT Optical upper limits
  75. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  76. GRB 241229B: Swift-BAT refined analysis
  77. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  78. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  79. GRB241229B: UVOT upper limits
  80. GRB 241228B: Fermi GBM Observation
  81. GRB 241228B: Swift-XRT afterglow detection
  82. GRB 241229B: Fermi GBM Observation
  83. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  84. GRB 241228A: Mondy optical afterglow observations
  85. GRB 241229A: GOTO optical upper limits
  86. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  87. GRB 241228A: NOT optical upper limits
  88. GRB 241228B: LCO optical observation
  89. GRB 241228A: Swift-BAT refined analysis
  90. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 241228A: Fermi GBM Observation
  92. GRB241228B: GROWTH-India Telescope optical observations
  93. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  94. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  95. GRB 241228A: GROWTH-India telescope optical upper limit
  96. GRB 241228B: TRT optical counterpart confirmation
  97. GRB 241228A: Swift-XRT refined Analysis
  98. GRB 241228A: Swift/UVOT Upper Limits
  99. GRB 241228A: Enhanced Swift-XRT position
  100. GRB 241228A: Swift detection of a burst

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